Re: [CentOS] Virtualization platform choice
On Mon, Mar 28, 2011 at 08:59:09AM -0400, Steve Thompson wrote: On Mon, 28 Mar 2011, Pasi Kärkkäinen wrote: On Sun, Mar 27, 2011 at 09:41:04AM -0400, Steve Thompson wrote: First. With Xen I was never able to start more than 30 guests at one time with any success; the 31st guest always failed to boot or crashed during booting, no matter which guest I chose as the 31st. With KVM I chose to add more guests to see if it could be done, with the result that I now have 36 guests running simultaneously. Hmm.. I think I've seen that earlier. I *think* it was some trivial thing to fix, like increasing number of available loop devices or so. I tried that, and other things, but was never able to make it work. I was using max_loop=64 in the end, but even with a larger number I couldn't start more than 30 guests. Number 31 would fail to boot, and would boot successfully if I shut down, say, #17. Then #17 would fail to boot, and so on. Ok. I have a link somewhere about how to fix that, but I can't seem to be able to find it now. Hmm.. Windows 7 might be too new for Xen 3.1 in el5, so for win7 upgrading to xen 3.4 or 4.x helps. (gitco.de has newer xen rpms for el5 if you're ok with thirdparty rpms). Point taken; I realize this. Third. I was never able to successfully complete a PXE-based installation under Xen. No problems with KVM. That's weird. I do that often. What was the problem? I use the DHCP server (on the host) to supply all address and name information, and this works without any issues. In the PXE case, I was never able to get the guest to communicate with the server for long enough to fully load pxelinux.0, in spite of the bridge setup. I have no idea why; it's not exactly rocket science either. Ok. Can you post more info about the benchmark? How many vcpus did the VMs have? How much memory? Were the VMs 32b or 64b ? The benchmark is just a make of a large package of my own implementation. A top-level makefile drives a series of makes of a set of sub-packages, 33 of them. It is a compilation of about 1100 C and C++ source files, including generation of dependencies and binaries, and running a set of perl scripts (some of which generate some of the C source). All of the sources and target directories were NFS volumes; only the local O/S disks were virtualized. I used 1 vcpu per guest and either 512MB or 1GB of memory. The results I showed were for 64-bit guests with 512MB memory, but they were qualitatively the same for 32-bit guests. Increasing memory from 512MB to 1GB made no significant difference to the timings. Some areas of the build are serial by nature; the result of 14:38 for KVM w/virtio was changed to 9:52 with vcpu=2 and make -j2. So it's a fork-heavy workload.. I'll try to make some benchmarks/comparisons soon aswell, also with other workloads. The 64-bit HVM guests w/o PV were quite a bit faster than the 32-bit HVM guests, as expected. I also had some Fedora diskless guests (no PV) using an NFS root, in which situation the 32-bit guests were faster than the 64-bit guests (and both were faster than the HVM guests w/o PV). These used kernels that I built myself. I did not compare Xen vs KVM with vcpu 1. Ok. Did you try Xen HVM with PV drivers? Yes, but I don't have the exact timings to hand anymore. They were faster than the non-PV case but still slower than KVM w/virtio. Yep. Fifth: I love being able to run top/iostat/etc on the host and see just what the hardware is really up to, and to be able to overcommit memory. xm top and iostat in dom0 works well for me :) I personally don't care much for xm top, and it doesn't help anyway if you're not running as root or have sudo access, or if you'd like to read performance info for the whole shebang via /proc (as I do). -- Pasi ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On 29/03/11 21:13, Kenni Lund wrote: Den 29/03/2011 15.41 skrev David Sommerseth d...@users.sourceforge.net: [...snip...] Thanks a lot for good information! The main problem is Windows guests, which easily chokes on hardware changes (forced reactivation of Windows or unbootable with BSOD). Each qemu-kvm version will behave differently, so moving from one major qemu-kvm version to another (0.1x - 0.1y), will most likely change the virtual hardware seen by the guest, unless you have libvirt etc. configured to keep track of the guest hardware. Do you know how to set up this? Or where to look for more details about this? I do have one Windows guest, and I can't break this one. If it's only Linux guests, it should work fine when moving the guests between any recent Linux distribution with KVM. Of course, if you don't use libvirt or a similar management solution, the hardware in the guest will likely change, for example causing your MAC-addresses of your NICs to change, etc, when moving to a new KVM host. It's all using libvirt already, so this should be pretty much the same. kind regards, David Sommerseth ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
2011/3/31 David Sommerseth d...@users.sourceforge.net: On 29/03/11 21:13, Kenni Lund wrote: The main problem is Windows guests, which easily chokes on hardware changes (forced reactivation of Windows or unbootable with BSOD). Each qemu-kvm version will behave differently, so moving from one major qemu-kvm version to another (0.1x - 0.1y), will most likely change the virtual hardware seen by the guest, unless you have libvirt etc. configured to keep track of the guest hardware. Do you know how to set up this? Or where to look for more details about this? I do have one Windows guest, and I can't break this one. AFAIR, the BSOD I've seen while moving Windows 2003 Server guests to new hosts (Fedora 7-8-9-10-11-CentOS5), was caused by old VirtIO guest block drivers. If you've installed recent VirtIO drivers in the guest (like virtio-win from Fedora) and are using a recent kernel/qemu-kvm on the host, then I don't think you'll have any BSOD or breakage of the guest. You'll need to reactivate once, but that should be it. If it was me who were going to move from to CentOS/SL 6 from a non-RH distribution with a different libvirt/qemu-kvm version, I would not use the old configuration file directly. Instead I would create a similar guest from scratch with virt-manager/virt-install, shut down the guest before installing anything, overwrite the new (empty) image with your old backup image and then compare the old XML configuration with the new one and manually move over some specific configurations, if needed. On first boot, you'll probably have to reactivate Windows, but at least now you know that the libvirt XML-configuration for the guest should be compatible with CentOS/SL 6+, and hence have stable guest hardware in future host upgrades. You can read some more about it here: http://fedoraproject.org/wiki/Features/KVM_Stable_PCI_Addresses http://fedoraproject.org/wiki/Features/KVM_Stable_Guest_ABI Best regards Kenni ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On 27/03/11 11:57, Jussi Hirvi wrote: Some may be bored with the subject - sorry... Still not decided about virtualization platform for my webhotel v2 (ns, mail, web servers, etc.). KVM would be a natural way to go, I suppose, only it is too bad CentOS 6 will not be out in time for me - I guess KVM would be more mature in CentOS 6. I believe KVM was introduced in RHEL5.4, so I presume CentOS5.5 have a working KVM support as well, in addition to Xen. Of course, it will be even better with CentOS6. For the impatient souls, ScientificLinux 6.0 is released - even though, discussions lately in this list raises some concerns regarding how good the binary compatibility is in SL6, compared to CentOS6. This makes me wondering how well it would go to migrate from SL6 to CentOS 6, if all KVM guests are on dedicated/separate LVM volumes and that you take a backup of /etc/libvirt. So when CentOS6 is released, scratch SL6 and install CentOS6, put back the SL6 libvirt configs ... would there be any issues in such an approach? And what about other KVM based host OSes? kind regards, David Sommerseth ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Tue, Mar 29, 2011 at 2:41 PM, David Sommerseth d...@users.sourceforge.net wrote: On 27/03/11 11:57, Jussi Hirvi wrote: Some may be bored with the subject - sorry... Still not decided about virtualization platform for my webhotel v2 (ns, mail, web servers, etc.). KVM would be a natural way to go, I suppose, only it is too bad CentOS 6 will not be out in time for me - I guess KVM would be more mature in CentOS 6. I believe KVM was introduced in RHEL5.4, so I presume CentOS5.5 have a working KVM support as well, in addition to Xen. Of course, it will be even better with CentOS6. For the impatient souls, ScientificLinux 6.0 is released - even though, discussions lately in this list raises some concerns regarding how good the binary compatibility is in SL6, compared to CentOS6. If it's good enough for Fermilab/CERN then it's prolly good enough for many (even most) people on this list, imho. :) ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
Den 29/03/2011 15.41 skrev David Sommerseth d...@users.sourceforge.net: This makes me wondering how well it would go to migrate from SL6 to CentOS 6, if all KVM guests are on dedicated/separate LVM volumes and that you take a backup of /etc/libvirt. So when CentOS6 is released, scratch SL6 and install CentOS6, put back the SL6 libvirt configs ... would there be any issues in such an approach? I would not expect any issues at all, I would expect it to just work. As long as you use CentOS6+/SL6+ (or Fedora 12+) *with* the libvirtd/virsh/virt-manager management tools, you shouldn't run into any major problems. This is because RH has implemented a stable guest ABI and stable guest PCI addresses, so the virtual hardware will remain the same on different KVM/libvirt hosts. And what about other KVM based host OSes? That depends on a lot of things...in general, if you're not using one of the RH-based distributions mentioned above, use the latest version of the distribution in question, to hopefully receive some of the upstreamed bits from the RH-distributions. Luckily things are slowly stabilizing, so it should only be a question of time, before any distribution with a recent kernel, recent qemu-kvm executable and a recent libvirt version, should be compatible with each other in terms of moving KVM-guests around. The main problem is Windows guests, which easily chokes on hardware changes (forced reactivation of Windows or unbootable with BSOD). Each qemu-kvm version will behave differently, so moving from one major qemu-kvm version to another (0.1x - 0.1y), will most likely change the virtual hardware seen by the guest, unless you have libvirt etc. configured to keep track of the guest hardware. If it's only Linux guests, it should work fine when moving the guests between any recent Linux distribution with KVM. Of course, if you don't use libvirt or a similar management solution, the hardware in the guest will likely change, for example causing your MAC-addresses of your NICs to change, etc, when moving to a new KVM host. Best regards Kenni ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Sun, Mar 27, 2011 at 09:41:04AM -0400, Steve Thompson wrote: The slightly longer story... First. With Xen I was never able to start more than 30 guests at one time with any success; the 31st guest always failed to boot or crashed during booting, no matter which guest I chose as the 31st. With KVM I chose to add more guests to see if it could be done, with the result that I now have 36 guests running simultaneously. Hmm.. I think I've seen that earlier. I *think* it was some trivial thing to fix, like increasing number of available loop devices or so. Second. I was never able to keep a Windows 7 guest running under Xen for more than a few days at a time without a BSOD. I haven't seen a single crash under KVM. Hmm.. Windows 7 might be too new for Xen 3.1 in el5, so for win7 upgrading to xen 3.4 or 4.x helps. (gitco.de has newer xen rpms for el5 if you're ok with thirdparty rpms). Then again xen in el5.6 might have fixes for win7, iirc. Third. I was never able to successfully complete a PXE-based installation under Xen. No problems with KVM. That's weird. I do that often. What was the problem? Fourth. My main work load consists of a series of builds of a package of about 1100 source files and about 500 KLOC's; all C and C++. Here are the elapsed times (min:sec) to build the package on a CentOS 5 guest (1 vcpu), each time with the guest being the only active guest (although the others were running). Sources come from NFS, and targets are written to NFS, with the host being the NFS server. * Xen HVM guest (no pv drivers): 29:30 * KVM guest, no virtio drivers: 23:52 * KVM guest, with virtio: 14:38 Can you post more info about the benchmark? How many vcpus did the VMs have? How much memory? Were the VMs 32b or 64b ? Did you try Xen HVM with PV drivers? I've been planning to benchmarks myself aswell so just curious. Fifth: I love being able to run top/iostat/etc on the host and see just what the hardware is really up to, and to be able to overcommit memory. xm top and iostat in dom0 works well for me :) -- Pasi ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Mon, 28 Mar 2011, Pasi Kärkkäinen wrote: On Sun, Mar 27, 2011 at 09:41:04AM -0400, Steve Thompson wrote: First. With Xen I was never able to start more than 30 guests at one time with any success; the 31st guest always failed to boot or crashed during booting, no matter which guest I chose as the 31st. With KVM I chose to add more guests to see if it could be done, with the result that I now have 36 guests running simultaneously. Hmm.. I think I've seen that earlier. I *think* it was some trivial thing to fix, like increasing number of available loop devices or so. I tried that, and other things, but was never able to make it work. I was using max_loop=64 in the end, but even with a larger number I couldn't start more than 30 guests. Number 31 would fail to boot, and would boot successfully if I shut down, say, #17. Then #17 would fail to boot, and so on. Hmm.. Windows 7 might be too new for Xen 3.1 in el5, so for win7 upgrading to xen 3.4 or 4.x helps. (gitco.de has newer xen rpms for el5 if you're ok with thirdparty rpms). Point taken; I realize this. Third. I was never able to successfully complete a PXE-based installation under Xen. No problems with KVM. That's weird. I do that often. What was the problem? I use the DHCP server (on the host) to supply all address and name information, and this works without any issues. In the PXE case, I was never able to get the guest to communicate with the server for long enough to fully load pxelinux.0, in spite of the bridge setup. I have no idea why; it's not exactly rocket science either. Can you post more info about the benchmark? How many vcpus did the VMs have? How much memory? Were the VMs 32b or 64b ? The benchmark is just a make of a large package of my own implementation. A top-level makefile drives a series of makes of a set of sub-packages, 33 of them. It is a compilation of about 1100 C and C++ source files, including generation of dependencies and binaries, and running a set of perl scripts (some of which generate some of the C source). All of the sources and target directories were NFS volumes; only the local O/S disks were virtualized. I used 1 vcpu per guest and either 512MB or 1GB of memory. The results I showed were for 64-bit guests with 512MB memory, but they were qualitatively the same for 32-bit guests. Increasing memory from 512MB to 1GB made no significant difference to the timings. Some areas of the build are serial by nature; the result of 14:38 for KVM w/virtio was changed to 9:52 with vcpu=2 and make -j2. The 64-bit HVM guests w/o PV were quite a bit faster than the 32-bit HVM guests, as expected. I also had some Fedora diskless guests (no PV) using an NFS root, in which situation the 32-bit guests were faster than the 64-bit guests (and both were faster than the HVM guests w/o PV). These used kernels that I built myself. I did not compare Xen vs KVM with vcpu 1. Did you try Xen HVM with PV drivers? Yes, but I don't have the exact timings to hand anymore. They were faster than the non-PV case but still slower than KVM w/virtio. Fifth: I love being able to run top/iostat/etc on the host and see just what the hardware is really up to, and to be able to overcommit memory. xm top and iostat in dom0 works well for me :) I personally don't care much for xm top, and it doesn't help anyway if you're not running as root or have sudo access, or if you'd like to read performance info for the whole shebang via /proc (as I do). Steve___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On 3/27/2011 3:07 PM, Jure Pečar wrote: It's interesting that nobody so far mentioned openVZ I wouldn't use it since being bitten by its lack of swap support. I run a couple of web sites on a fairly heavy web stack which loads up a bunch of dependencies that don't actually end up being used by my site, but because there is no swap, all that unused code eats real RAM. Because of that, I had to upgrade to a 512 MB VPS hosting plan from a 256 MB plan. My sites initially ran just fine under the 256 MB plan but after adding just one feature to my sites which used one of the piggier features in the web stack, it pushed me over the limit and I had to upgrade. If the VPS could use swap, I'm sure enough of the web stack would remain swapped out that I could have continued using the 256 MB plan. My VPS provider may find OpenVZ to be efficient than Xen, but it cost me about 50% more in hosting fees. That's less efficient in my book. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
Please also consider OpenNode - http://opennode.activesys.org - a CentOS based KVM full virtualization + OpenVZ linux containers solution. Supports VM templating and live migration, etc - with easy bare metal setup. Cheers, -- -- Andres Toomsalu, and...@active.ee On 27.03.2011, at 12:57, Jussi Hirvi wrote: Some may be bored with the subject - sorry... Still not decided about virtualization platform for my webhotel v2 (ns, mail, web servers, etc.). KVM would be a natural way to go, I suppose, only it is too bad CentOS 6 will not be out in time for me - I guess KVM would be more mature in CentOS 6. Any experience with the free VMware vSphere Hypervisor?. (It was formerly known as VMware ESXi Single Server or free ESXi.) http://www.vmware.com/products/vsphere-hypervisor/overview.html I would need a tutorial about that... For example, does that run without a host OS? Can it be managed only via Win clients? Issues with CentOS 4/5 guests (all my systems are currently CentOS 4/5). - Jussi -- Jussi Hirvi * Green Spot Topeliuksenkatu 15 C * 00250 Helsinki * Finland Tel. +358 9 493 981 * Mobile +358 40 771 2098 (only sms) jussi.hi...@greenspot.fi * http://www.greenspot.fi ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On 03/27/11 11:57, Jussi Hirvi wrote: Some may be bored with the subject - sorry... Still not decided about virtualization platform for my webhotel v2 (ns, mail, web servers, etc.). KVM would be a natural way to go, I suppose, only it is too bad CentOS 6 will not be out in time for me - I guess KVM would be more mature in CentOS 6. Any experience with the free VMware vSphere Hypervisor?. (It was formerly known as VMware ESXi Single Server or free ESXi.) http://www.vmware.com/products/vsphere-hypervisor/overview.html I would need a tutorial about that... For example, does that run without a host OS? Can it be managed only via Win clients? Issues with CentOS 4/5 guests (all my systems are currently CentOS 4/5). - Jussi VMware ESXi is definitely a good choice. I use it at work (the free version as well) and haven't regretted it. No tutorials needed, everything's pretty straightforward. Yes, it can only be graphically managed from Windows clients (vsphere client), however the command line tools are available for Linux as well. Tried running the vsphere client using wine but that didn't work. No issues with CentOS 5 guests here. Glenn ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On 03/27/2011 02:57 AM, Jussi Hirvi wrote: Some may be bored with the subject - sorry... Still not decided about virtualization platform for my webhotel v2 (ns, mail, web servers, etc.). KVM would be a natural way to go, I suppose, only it is too bad CentOS 6 will not be out in time for me - I guess KVM would be more mature in CentOS 6. Any experience with the free VMware vSphere Hypervisor?. (It was formerly known as VMware ESXi Single Server or free ESXi.) http://www.vmware.com/products/vsphere-hypervisor/overview.html I would need a tutorial about that... For example, does that run without a host OS? Can it be managed only via Win clients? Issues with CentOS 4/5 guests (all my systems are currently CentOS 4/5). I'm currently using Ubuntu Server 10.04-LTS as a host for KVM running CentOS5.5 guests I migrated from VMware Server 2. Works fine. A nice feature of current generation KVM is that you are supposed to be able to do live migration even without shared storage (although I haven't tested that yet). I wrote some custom scripts to allow me to take LVM snapshots for whole-image backups and I'm pretty happy with the who setup. The only corners I encountered were 1) A lack of documentation on how to configure bridging over bonded interfaces for the host server. It turned out to be fairly easy - just not clearly documented anyplace I could find. 2) The default configuration for rebooting/shutting dow the host server just 'shoots the guests in the head' rather than having them shutdown cleanly. :( You will want to write something to make sure they get shutdown properly instead. -- Benjamin Franz ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
Any experience with the free VMware vSphere Hypervisor?. (It was formerly known as VMware ESXi Single Server or free ESXi.) http://www.vmware.com/products/vsphere-hypervisor/overview.html I would need a tutorial about that... For example, does that run without a host OS? Can it be managed only via Win clients? Issues with CentOS 4/5 guests (all my systems are currently CentOS 4/5). vSphere ESX(i) is good product. It runs on bare metal so there is no OS underneath it. ESX has a linux based environment that sort of runs at the hypervisor level that people use for basic admin but VMware is trying to phase that out as most everything you can do with ESX's console can be done through ESXi's API's and the remote CLI. Only downside to the free version is certain API's are unavailable and if you need those features you may have to go to a paid version. -- Drew Nothing in life is to be feared. It is only to be understood. --Marie Curie ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
2011/3/27 Drew drew@gmail.com: Any experience with the free VMware vSphere Hypervisor?. (It was formerly known as VMware ESXi Single Server or free ESXi.) http://www.vmware.com/products/vsphere-hypervisor/overview.html I would need a tutorial about that... For example, does that run without a host OS? Can it be managed only via Win clients? Issues with CentOS 4/5 guests (all my systems are currently CentOS 4/5). vSphere ESX(i) is good product. It runs on bare metal so there is no OS underneath it. ESX has a linux based environment that sort of runs at the hypervisor level that people use for basic admin but VMware is trying to phase that out as most everything you can do with ESX's console can be done through ESXi's API's and the remote CLI. Only downside to the free version is certain API's are unavailable and if you need those features you may have to go to a paid version. Biggest problem in free esxi is that it lacks backup vcb api, so full image backups are almost impossible under free esxi host .. -- Eero ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Sun, Mar 27, 2011 at 8:53 AM, Drew drew@gmail.com wrote:
Any experience with the free VMware vSphere Hypervisor?. (It was
formerly known as VMware ESXi Single Server or free ESXi.)
http://www.vmware.com/products/vsphere-hypervisor/overview.html
I would need a tutorial about that... For example, does that run without
a host OS? Can it be managed only via Win clients? Issues with CentOS
4/5 guests (all my systems are currently CentOS 4/5).
vSphere ESX(i) is good product. It runs on bare metal so there is no
OS underneath it. ESX has a linux based environment that sort of runs
at the hypervisor level that people use for basic admin but VMware is
trying to phase that out as most everything you can do with ESX's
console can be done through ESXi's API's and the remote CLI.
I like vSphere in corporate environments, and LabManager with it for
burning guest images very quickly. The VMWareTools are not as
integrated as I would like, and their RPM names are quite misleading.
(The name of the file does not match the name of the actual RPM
reqported by `rpm -qf --%{name}-%{version}-%{release}.%{arch}.rpm\n',
and it's not as well integrated for kernel changes or host cloning as
I'd like. (Ask if you're curious.) But for corporate grade
virtualization, well built management tools, and corporate support,
they're very hard to beat. And for virtualizing weird old setups, like
SCO OpenServer 5.0.x, they're the only thing I tested that worked.
KVM was a dog in testing under CentOS and RHEL 5.x. The bridged
networking has *NO* network configuration tool that understands how to
set it up, you have to do it manually, and that's a deficit I've
submitted upstream as an RFE. It may work well with CentOS and RHEL 6,
i've not had a chance to test it.
VirtualBox is friendly, lightweight, and I'm using it right now under
MacOS X for a Debian box, and on Windows boxes for testing Linux
environments. Works quite well, friendly interfaces, very quick to
learn, I like it a light for one-off setups.
Xen, I did a stack of work with for CentOS 4 a few years ago. It
worked well, particularly with the para-virtualized kernels to improve
performance. (Don't virtualize things you don't have to!!! Uses custom
kernels to let the guest and server not waste time virtualizing IO
requests, especially for disk IO). I've not played with its management
tools since, and it didn't work well with virtualizing odd old OS's.
(I wanted to use it for OpenServer, but the support team who came
out to demonstrate it couldn't even get the keyboards interacting
reliably for the installation. It was a complete failure for that
project.)
You've got a lot of choices. I'd start with assessing what you need
for your guest environments, and where it's going to be managed from,
and be sure that you've got access to the management tools.
Only downside to the free version is certain API's are unavailable and
if you need those features you may have to go to a paid version.
This is true for everything in life.
___
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Re: [CentOS] Virtualization platform choice
On Sun, Mar 27, 2011 at 9:16 AM, Eero Volotinen eero.voloti...@iki.fi wrote: 2011/3/27 Drew drew@gmail.com: Any experience with the free VMware vSphere Hypervisor?. (It was formerly known as VMware ESXi Single Server or free ESXi.) http://www.vmware.com/products/vsphere-hypervisor/overview.html I would need a tutorial about that... For example, does that run without a host OS? Can it be managed only via Win clients? Issues with CentOS 4/5 guests (all my systems are currently CentOS 4/5). vSphere ESX(i) is good product. It runs on bare metal so there is no OS underneath it. ESX has a linux based environment that sort of runs at the hypervisor level that people use for basic admin but VMware is trying to phase that out as most everything you can do with ESX's console can be done through ESXi's API's and the remote CLI. Only downside to the free version is certain API's are unavailable and if you need those features you may have to go to a paid version. Biggest problem in free esxi is that it lacks backup vcb api, so full image backups are almost impossible under free esxi host .. If you have some money to spend you can solve the backup problem with VMware's $500 entry level license. The license gives you the vCenter server software, which can manage 3 ESXi hosts and unlocks a number of capabilities, like cloning and offline migration. For around $1000 per server you can look at Veam or Vizioncore for backups. Overall you can't beat the price for the reliability and ease of use. Since ESXi is a bare metal hypervisior it doesn't have as many security vulnerabilities discovered which means less reboots of the host system. I have been using ESXi since 3.5 with around 8 ESXi servers now and 50 guests. I have not had a crash of the host ESXi host and the advanced capabilities (vMotion, Storage vMotion and Enhanced vMotion Capability (EVC)) have just worked, these do not work with the $500 license. Ryan ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Sun, 27 Mar 2011, Jussi Hirvi wrote: KVM would be a natural way to go, I suppose, only it is too bad CentOS 6 will not be out in time for me - I guess KVM would be more mature in CentOS 6. I have been using Xen with much success for several years, now with two CentOS 5.5 x86_64 Dom0's, hosting 29 (mixed Linux and Windows) and 30 (all Windows) guests respectively, using only packages from the distro along with the GPLPV drivers on the Windows guests (so it's Xen 3.1, not the latest). A couple of weeks ago I decided (on the first of these hosts) to give KVM a look, since I was able to take the machine down for a while. All guests use LVM volumes, and were unchanged between Xen and KVM (modulo pv drivers). The host is a Dell PE2900 with 24 GB memory and E5345 processors (8 cores). Bridged mode networking. What follows is obviously specific to my environment, so YMMV. The short story is that I plan to keep using KVM. It has been absolutely solid and without any issues whatsoever, and performance is significantly better than Xen in all areas that I have measured (and also in the feels good benchmark). Migration from Xen to KVM was almost trivially simple. The slightly longer story... First. With Xen I was never able to start more than 30 guests at one time with any success; the 31st guest always failed to boot or crashed during booting, no matter which guest I chose as the 31st. With KVM I chose to add more guests to see if it could be done, with the result that I now have 36 guests running simultaneously. Second. I was never able to keep a Windows 7 guest running under Xen for more than a few days at a time without a BSOD. I haven't seen a single crash under KVM. Third. I was never able to successfully complete a PXE-based installation under Xen. No problems with KVM. Fourth. My main work load consists of a series of builds of a package of about 1100 source files and about 500 KLOC's; all C and C++. Here are the elapsed times (min:sec) to build the package on a CentOS 5 guest (1 vcpu), each time with the guest being the only active guest (although the others were running). Sources come from NFS, and targets are written to NFS, with the host being the NFS server. * Xen HVM guest (no pv drivers): 29:30 * KVM guest, no virtio drivers: 23:52 * KVM guest, with virtio: 14:38 Fifth: I love being able to run top/iostat/etc on the host and see just what the hardware is really up to, and to be able to overcommit memory. Steve ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Sun, Mar 27, 2011 at 9:41 AM, Steve Thompson s...@vgersoft.com wrote: On Sun, 27 Mar 2011, Jussi Hirvi wrote: KVM would be a natural way to go, I suppose, only it is too bad CentOS 6 will not be out in time for me - I guess KVM would be more mature in CentOS 6. I have been using Xen with much success for several years, now with two CentOS 5.5 x86_64 Dom0's, hosting 29 (mixed Linux and Windows) and 30 (all Windows) guests respectively, using only packages from the distro along with the GPLPV drivers on the Windows guests (so it's Xen 3.1, not the latest). A couple of weeks ago I decided (on the first of these hosts) to give KVM a look, since I was able to take the machine down for a while. All guests use LVM volumes, and were unchanged between Xen and KVM (modulo pv drivers). The host is a Dell PE2900 with 24 GB memory and E5345 processors (8 cores). Bridged mode networking. What follows is obviously specific to my environment, so YMMV. The short story is that I plan to keep using KVM. It has been absolutely solid and without any issues whatsoever, and performance is significantly better than Xen in all areas that I have measured (and also in the feels good benchmark). Migration from Xen to KVM was almost trivially simple. The slightly longer story... First. With Xen I was never able to start more than 30 guests at one time with any success; the 31st guest always failed to boot or crashed during booting, no matter which guest I chose as the 31st. With KVM I chose to add more guests to see if it could be done, with the result that I now have 36 guests running simultaneously. Second. I was never able to keep a Windows 7 guest running under Xen for more than a few days at a time without a BSOD. I haven't seen a single crash under KVM. Third. I was never able to successfully complete a PXE-based installation under Xen. No problems with KVM. How did you get the PXE working? I had real problems. Mind you, that was RHEL 5.4 and CentOS 5.4 for the server host, so it may have improved. And do you have widgets for setting up the necessary bridged networking? I left mine behind at a consulting gig, and haven't asked for copies of them. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Sun, 27 Mar 2011, Nico Kadel-Garcia wrote: How did you get the PXE working? I already had a PXE server for physical hosts, so I just did a virt-install with the --pxe switch, and it worked first time. The MAC address was pre-defined and known to the DHCP server. I installed both Linux and Windows guests with PXE. And do you have widgets for setting up the necessary bridged networking? I edited the ifcfg-eth0 file on the host and added an ifcfg-br0, all by hand, and then rebooted. I didn't have to think about it again. /etc/sysconfig/network-scripts/ifcfg-eth0: DEVICE=eth0 HWADDR=xx:xx:xx:xx:xx:xx ONBOOT=yes BRIDGE=br0 NM_CONTROLLED=0 /etc/sysconfig/network-scripts/ifcfg-br0: DEVICE=br0 TYPE=Bridge BOOTPROTO=static BROADCAST=braddr IPADDR=ipaddr NETMASK=netmask NETWORK=network ONBOOT=yes For each guest, something like this was used: interface type='bridge' mac address='52:54:00:1d:58:cf'/ source bridge='br0'/ model type='virtio'/ /interface Steve ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
KVM was a dog in testing under CentOS and RHEL 5.x. The bridged networking has *NO* network configuration tool that understands how to set it up, you have to do it manually, and that's a deficit I've submitted upstream as an RFE. It may work well with CentOS and RHEL 6, i've not had a chance to test it. Back when I was searching for a suitable virtualization platform, I found no difference in performance between Xen and KVM. I liked both, but settled on KVM. ESXi back then was very limited in hardware support, so I never got to play with it much. People seem to like it. And it's true that bridged networking support in centos 5 requires that you set up it manually, but that's what led me to learn ifcfg scripts. It's so simple. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On 3/27/11 4:57 AM, Jussi Hirvi wrote: Some may be bored with the subject - sorry... Still not decided about virtualization platform for my webhotel v2 (ns, mail, web servers, etc.). KVM would be a natural way to go, I suppose, only it is too bad CentOS 6 will not be out in time for me - I guess KVM would be more mature in CentOS 6. Any experience with the free VMware vSphere Hypervisor?. (It was formerly known as VMware ESXi Single Server or free ESXi.) http://www.vmware.com/products/vsphere-hypervisor/overview.html I would need a tutorial about that... For example, does that run without a host OS? Can it be managed only via Win clients? Issues with CentOS 4/5 guests (all my systems are currently CentOS 4/5). The free ESXi version is very good. While it doesn't support all the bells and whistles of the paid version, there are hardly any disadvantages compared to running the VMs on physical machines. You do have to use a windows box to manage it (with the advantage of being able to use the media on the client for the install source), but once the guest networking is up you can use whatever you would use for remote access to a physical box (vnc, ssh, X, freenx, etc.) directly to the guest - so the windows box doesn't have to be server-quality or available all the time. You might even be able to use the converter tool to migrate your running systems there - I've usually been able to do that with windows systems but couldn't get it to recognize my linux boxes with software raid (and didn't try any others since they aren't that hard to re-create). By the way, the current version of ESXi permits ssh without the 'unsupported' hack so you can copy images over scp or to/from an nfs mount, but it's not all that much faster than running the converter tool on another machine anyway. -- Les Mikesell lesmikes...@gmail.com ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
Biggest problem in free esxi is that it lacks backup vcb api, so full image backups are almost impossible under free esxi host .. Not true at all, I use the ghettovcb script in the console and it works fine. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On 03/27/2011 07:10 AM, Steve Thompson wrote: On Sun, 27 Mar 2011, Nico Kadel-Garcia wrote: How did you get the PXE working? I already had a PXE server for physical hosts, so I just did a virt-install with the --pxe switch, and it worked first time. The MAC address was pre-defined and known to the DHCP server. I installed both Linux and Windows guests with PXE. And do you have widgets for setting up the necessary bridged networking? I edited the ifcfg-eth0 file on the host and added an ifcfg-br0, all by hand, and then rebooted. I didn't have to think about it again. /etc/sysconfig/network-scripts/ifcfg-eth0: DEVICE=eth0 HWADDR=xx:xx:xx:xx:xx:xx ONBOOT=yes BRIDGE=br0 NM_CONTROLLED=0 /etc/sysconfig/network-scripts/ifcfg-br0: DEVICE=br0 TYPE=Bridge BOOTPROTO=static BROADCAST=braddr IPADDR=ipaddr NETMASK=netmask NETWORK=network ONBOOT=yes For each guest, something like this was used: interface type='bridge' mac address='52:54:00:1d:58:cf'/ source bridge='br0'/ model type='virtio'/ /interface Steve ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos I setup a pxe boot server based on the instructions found here. https://help.ubuntu.com/community/PXEInstallMultiDistro https://help.ubuntu.com/community/PXEInstallMultiDistro It works fine for both physical machines and kvm VM's. My pxeboot server is running under ubuntu 10.04.2 in a kvm vm. If your pxeboot server needs to run under Redhat/CentOS, then you'll need to locate/install the packages mentioned on this web page, which should be pretty straight forward. Note the pxeboot server works fine for the install CDs and DVD's for all of the distributions that I've tried, Redhat, Fedora and Ubuntu. To boot live CDs I believe you need to convert the entire image into a tftp boot image which I think can be done using the fedora live cd creator tool (maybe it's in redhat now as well). I make the CD/DVD image available via NFS. On the PXE host I simply mount the ISO image under the NFS /export directory. Most of the install distributions provide the tftp images for pxeboot. On the redhat 6 CD you'll find vmlinuz and initrd.img in the /images/pxeboot directory. I just recently installed kvm virtualization on several redhat 6 hosts and one under Scientific Linux. The latest version of virt-manager (with recent updates installed) now supports setup of bridge devices from the GUI. You'll want to make sure to use virtio for performance and to disable the tso and gso tcp offload functions present in many ethernet cards which I do with the upstart script listed below. I am so far quite happy with kvm and happy to be able to run my management interface under linux instead of windows. #disable-tcpoffload - upstart script to modify tcp offload config for virtualization # description disable-tcpoffload start on started rc RUNLEVEL=[2345] stop on stopped rc RUNLEVEL=[!2345] task console output # env INIT_VERBOSE script set +e for interface in eth0 eth1 eth2 eth3; do /sbin/ethtool -K $interface gso off /sbin/ethtool -K $interface tso off done end script Nataraj ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On 03/27/11 2:57 AM, Jussi Hirvi wrote: Any experience with the free VMware vSphere Hypervisor?. (It was formerly known as VMware ESXi Single Server or free ESXi.) one downside to ESXi, it does not support any sort of software raid. Normally ESX is used with a SAN, which provides all RAID functionality, or with NFS based storage (again, the NFS server providing the raid), but if you use it with direct attached storage, you had better have a supported hardware raid controller.Most server kit from the big vendors is fully supported (HP,Dell,IBM). You can boot ESXi from a small CF card, as once its booted, it doesn't touch the boot device at all. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
You can boot ESXi from a small CF card, as once its booted, it doesn't touch the boot device at all. Yes it does, there are cron jobs for config backups etc. How does it remember config changes in a non-stateless deployment? ~ # cat /var/spool/cron/crontabs/root #syntax : minute hour day month dayofweek command 01 01 * * * /sbin/tmpwatch.sh 01 * * * * /sbin/auto-backup.sh #first minute of every hour (run every hour) ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Sun, Mar 27, 2011 at 11:07 PM, Jure Pečar pega...@nerv.eu.org wrote: On Sun, 27 Mar 2011 10:42:36 -0500 Les Mikesell lesmikes...@gmail.com wrote: On 3/27/11 4:57 AM, Jussi Hirvi wrote: Some may be bored with the subject - sorry... Still not decided about virtualization platform for my webhotel v2 (ns, mail, web servers, etc.). It's interesting that nobody so far mentioned openVZ or its commercial version, Virtuozzo. It's different than all major virtualization players (it's OS level virtualization, not hw level), but that makes it the only viable option for things like mass web hosting solutions. Try it out and see if it fits your requirements. -- OpenVZ / Virtuzzo is a joke and shouldn't be used for production purposes. Especially not in mass web hosting solutions - that's just asking for trouble. -- Kind Regards Rudi Ahlers SoftDux Website: http://www.SoftDux.com Technical Blog: http://Blog.SoftDux.com Office: 087 805 9573 Cell: 082 554 7532 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
It's interesting that nobody so far mentioned openVZ or its commercial version, Virtuozzo. It's different than all major virtualization players (it's OS level virtualization, not hw level), but that makes it the only viable option for things like mass web hosting solutions. Try it out and see if it fits your requirements. The two things that always comes to mind when I am considering a virtualization solution is extent of tool set/support, and the general acceptance of the technology. For those two reasons I nearly always implement VMware, it has a mature set of tools, a wide range of functionality, and sits at a very manageable price point. No true open source solution really comes close, you can approximate parts of it, but in the end it turns into a support issue that can pose a significant headache. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Sun, 27 Mar 2011 14:21:45 -0700 David Brian Chait dch...@invenda.com wrote: The two things that always comes to mind when I am considering a virtualization solution is extent of tool set/support, and the general acceptance of the technology. For those two reasons I nearly always implement VMware, it has a mature set of tools, a wide range of functionality, and sits at a very manageable price point. No true open source solution really comes close, you can approximate parts of it, but in the end it turns into a support issue that can pose a significant headache. True. I've deployed Virtuozzo for a large web hosting company and found it superior to vmware in about every aspect that mattered in a web hosting environment. OpenVZ on the other hand is about at the same level as xen, kvm and similiar opensource solutions. Well, not so much a solution, but a building block to help you build your own solution to your particular problem. -- Jure Pečar http://jure.pecar.org http://f5j.eu ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
I've deployed Virtuozzo for a large web hosting company and found it superior to vmware in about every aspect that mattered in a web hosting environment. Well.. eh. as you might know that virtuozzo/openvz does not provide kernel isolation. Mainly this means than one kernel exploit can provide full access to all openvz/virtuozzo containers. -- Eero ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Sun, Mar 27, 2011 at 11:50 PM, Eero Volotinen eero.voloti...@iki.fi wrote: I've deployed Virtuozzo for a large web hosting company and found it superior to vmware in about every aspect that mattered in a web hosting environment. Well.. eh. as you might know that virtuozzo/openvz does not provide kernel isolation. Mainly this means than one kernel exploit can provide full access to all openvz/virtuozzo containers. -- . and one overloaded containter can take down the whole server as well. -- Kind Regards Rudi Ahlers SoftDux Website: http://www.SoftDux.com Technical Blog: http://Blog.SoftDux.com Office: 087 805 9573 Cell: 082 554 7532 ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Mon, 28 Mar 2011 00:10:45 +0200 Rudi Ahlers r...@softdux.com wrote: On Sun, Mar 27, 2011 at 11:50 PM, Eero Volotinen eero.voloti...@iki.fi wrote: I've deployed Virtuozzo for a large web hosting company and found it superior to vmware in about every aspect that mattered in a web hosting environment. Well.. eh. as you might know that virtuozzo/openvz does not provide kernel isolation. Mainly this means than one kernel exploit can provide full access to all openvz/virtuozzo containers. The same is true for solutions like vmware. Just google for all the blue pill talks. It's a theoretical risk that is small enough to be irrelevant. . and one overloaded containter can take down the whole server as well. That's simply FUD. -- Jure Pečar http://jure.pecar.org http://f5j.eu ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
Well.. eh. as you might know that virtuozzo/openvz does not provide kernel isolation. Mainly this means than one kernel exploit can provide full access to all openvz/virtuozzo containers. The same is true for solutions like vmware. Just google for all the blue pill talks. It's a theoretical risk that is small enough to be irrelevant. WebServers running buggy php software provides (easy) way to execute local kernel exploits. -- Eero ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On Mon, 28 Mar 2011 01:26:38 +0300 Eero Volotinen eero.voloti...@iki.fi wrote: The same is true for solutions like vmware. Just google for all the blue pill talks. It's a theoretical risk that is small enough to be irrelevant. WebServers running buggy php software provides (easy) way to execute local kernel exploits. Yes and I've dealt with my share of them. None ever exploited some virtuozzo vulnerability. In fact many of them failed because they were run on a VPS. I trust the russian guys to know their way with C code and kernel fu. That's why many of the virtuozzo core parts are becoming part of the linus tree, cgroups being just one of the top of my head. See, there's even a nice wiki article: http://wiki.centos.org/HowTos/Virtualization/OpenVZ I understand that vmware has much stronger marketing machine, however that does not mean that their technology is somehow better. Their offer is a reasonable choice for many scenarios in IT, mass web hosting is unfortunately not one of them. As any competent admin will tell you, use the right tool for the right job. It's good to have choice. -- Jure Pečar http://jure.pecar.org http://f5j.eu ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
I understand that vmware has much stronger marketing machine, however that does not mean that their technology is somehow better. Their offer is a reasonable choice for many scenarios in IT, mass web hosting is unfortunately not one of them. As any competent admin will tell you, use the right tool for the right job. It's good to have choice. You can't honestly be comparing a 2.6b / year corporation that sells/develops enterprise scale products that serve nearly all of the Fortune 500 to a virtually unknown product sold by the maker of Parallels. They are not even close to being in the same league. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
David Brian Chait wrote: I understand that vmware has much stronger marketing machine, however that does not mean that their technology is somehow better. Their offer is a reasonable choice for many scenarios in IT, mass web hosting is unfortunately not one of them. As any competent admin will tell you, use the right tool for the right job. It's good to have choice. You can't honestly be comparing a 2.6b / year corporation that sells/develops enterprise scale products that serve nearly all of the Fortune 500 to a virtually unknown product sold by the maker of Parallels. They are not even close to being in the same league. Using that logic Micro$oft must be providing the best software on the planet ;-) ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos attachment: rkampen.vcf___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Virtualization platform choice
On 03/27/2011 09:00 AM, Jerry Franz wrote: On 03/27/2011 02:57 AM, Jussi Hirvi wrote: Some may be bored with the subject - sorry... Still not decided about virtualization platform for my webhotel v2 (ns, mail, web servers, etc.). KVM would be a natural way to go, I suppose, only it is too bad CentOS 6 will not be out in time for me - I guess KVM would be more mature in CentOS 6. Any experience with the free VMware vSphere Hypervisor?. (It was formerly known as VMware ESXi Single Server or free ESXi.) http://www.vmware.com/products/vsphere-hypervisor/overview.html I would need a tutorial about that... For example, does that run without a host OS? Can it be managed only via Win clients? Issues with CentOS 4/5 guests (all my systems are currently CentOS 4/5). I'm currently using Ubuntu Server 10.04-LTS as a host for KVM running CentOS5.5 guests I migrated from VMware Server 2. Works fine. A nice feature of current generation KVM is that you are supposed to be able to do live migration even without shared storage (although I haven't tested that yet). I wrote some custom scripts to allow me to take LVM snapshots for whole-image backups and I'm pretty happy with the who setup. The only corners I encountered were 1) A lack of documentation on how to configure bridging over bonded interfaces for the host server. It turned out to be fairly easy - just not clearly documented anyplace I could find. 2) The default configuration for rebooting/shutting dow the host server just 'shoots the guests in the head' rather than having them shutdown cleanly.:( You will want to write something to make sure they get shutdown properly instead. Once in a while I find it's useful to compromise just a little, so I use Scientific Linux 6 as the Host OS, and run a bunch of CentOS-5.5 Guest VMs. It all simply works. KVM has improved quite a bit, and the management tools work well. One thing that requires a bit of skill is getting bridging configured (which I simply did by hand from the RHEL-6 documentation). I'm happy with the result, and see no reason to replace the underlying SL-6 Host distro. SL-6 as the Host is rather slow to shut down gracefully and reboot, because it hibernates the Guest OSs, one at a time, rather than just killing them. Hibernation takes a while to write out to disk if you've assigned a lot of RAM to the Guests. Bootup has to restore the saved state, so that's a bit slow too. But it works very well. I use partitionable RAID arrays for the Guests, and assign a raw md device to each one rather than using the 'filesystem-in-a-file' method. It seems to be a bit faster, but there's a learning curve to understanding how it works. One thing I found a bit annoying is the very long time it takes for a Guest to format its filesystems on the RAID-6 md device assigned to it. That's mostly due to array checksum overhead. RAID-10 would be a *lot* faster but somewhat less robust ... you pick what's best for your own situation. Chuck ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
