Re: [CentOS] Slightly OT: First Time KVM and LVM on Centos
On Jun 20, 2011, at 9:56 AM, Kwan Lowe kwan.l...@gmail.com wrote: On Thu, Jun 16, 2011 at 8:59 AM, Les Mikesell lesmikes...@gmail.com wrote: There is no reason that should be true. Copying 20GB out of an LV should take exactly the same amount of time as copying 20GB out of a file. What about the destination? Wouldn't it likely be harder to find a place to put the LV copy than space to write a file? Or can you copy back and forth? -- I just copy the raw filesystem directly to the remote raw filesystem with dd over ssh. If needed you can dd the entire partition to a file also. With LVMs you can also mirror the LV across multiple LUNs, break the mirror, then move the other LUN to another system. You might have better performance using Clonezilla over ssh then dd. -Ross ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Slightly OT: First Time KVM and LVM on Centos
On Thu, Jun 16, 2011 at 8:59 AM, Les Mikesell lesmikes...@gmail.com wrote: There is no reason that should be true. Copying 20GB out of an LV should take exactly the same amount of time as copying 20GB out of a file. What about the destination? Wouldn't it likely be harder to find a place to put the LV copy than space to write a file? Or can you copy back and forth? -- I just copy the raw filesystem directly to the remote raw filesystem with dd over ssh. If needed you can dd the entire partition to a file also. With LVMs you can also mirror the LV across multiple LUNs, break the mirror, then move the other LUN to another system. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Slightly OT: First Time KVM and LVM on Centos
On 06/15/2011 05:52 PM, Ljubomir Ljubojevic wrote: Drawback is that such KVM guest is not as easy to move to another host if current host can not boot. Copying image and config files will be much faster. There is no reason that should be true. Copying 20GB out of an LV should take exactly the same amount of time as copying 20GB out of a file. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Slightly OT: First Time KVM and LVM on Centos
On 6/16/11 1:56 AM, Gordon Messmer wrote: On 06/15/2011 05:52 PM, Ljubomir Ljubojevic wrote: Drawback is that such KVM guest is not as easy to move to another host if current host can not boot. Copying image and config files will be much faster. There is no reason that should be true. Copying 20GB out of an LV should take exactly the same amount of time as copying 20GB out of a file. What about the destination? Wouldn't it likely be harder to find a place to put the LV copy than space to write a file? Or can you copy back and forth? -- Les Mikesell lesmikes...@gmail.com ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Slightly OT: First Time KVM and LVM on Centos
On 06/16/2011 05:59 AM, Les Mikesell wrote: What about the destination? Wouldn't it likely be harder to find a place to put the LV copy than space to write a file? Or can you copy back and forth? Yes, you can copy the content of a partition to a file and use it that way, or the reverse. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Slightly OT: First Time KVM and LVM on Centos
On 06/13/2011 02:00 PM, Jeff Boyce wrote: I am a novice system administrator and will soon be purchasing a new server to replacing an aging file server for my company. I am considering setting up the new server as a KVM host with two guests; one guest as the Samba file server and a second guest as a testing area. My old server was set up about 7 years ago and has a 5 disk raid 5 configuration without LVM. My first piece of advice would be to avoid RAID5. The performance is terrible. I understand the benefits of using LVM and KVM in the right circumstances, but have never used either of them. I have spent a couple of days over the last week trying to understand how to setup a KVM host with guests, but there is an area that I still don't understand; that is the relationship between the underlying raid partitions, LVM, and allocating space to a host and guests. That should be pretty simple... During the installation of the host system, you'll partition your drives as you need them. I try to keep mine simple, for example: http://home.dragonsdawn.net/kickstart/centos5 That configuration will put two partitions on each of two drives. Each drive gets a small partition which will be arranged in a RAID1 set; that RAID1 set is mounted at /boot. The other partition, which fills the rest of each disk, form another RAID1 set. That RAID1 set is an LVM physical volume. That PV forms a volume group named VolGroup. All of the host's filesystems and its swap are created on logical volumes inside that volume group. So on my simple setup, I have four partitions on two drives. Two partitions are used for /boot, and the other two are used for the physical volume. All filesystems other than /boot are on logical volumes. In that kickstart file, /var will fill all of the available space. On a KVM host, you'd want to set a fixed size for /var instead. That would leave you with some of your volume group unallocated when the installation is complete. When you set up your guests, you can start by allocating a new logical volume from your volume group. That LV will get a device file in /dev/mapper. When you set up your guest, you use that LV as the guest's disk. The guest will treat that LV as if it were a disk drive. The guess will create partitions on it (and possibly LVM of its own) and filesystems on top of those partitions or logical volumes just as if it were a physical machine with a disk drive. Many of the standard search term combinations in Google don't seem to be getting me anywhere. From what I have read so far I think that I want to have my file server guest using a raw partition rather than an image file, but I haven't found anything with examples or best-practices guidance for partitioning or volume management with hosts and guest VMs. So I am hoping that someone here can give me some pointers, or point me to some clear how-to's somewhere. Any help is appreciated. Thanks. That's probably true. image file backed guests are a whole lot slower than guests that run on partitions or logical volumes. Logical volumes are the easiest option to manage, with good performance characteristics. Hopefully that made sense. Ask questions if not. ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Slightly OT: First Time KVM and LVM on Centos
Gordon Messmer wrote: That's probably true. image file backed guests are a whole lot slower than guests that run on partitions or logical volumes. Logical volumes are the easiest option to manage, with good performance characteristics. Hopefully that made sense. Ask questions if not. Drawback is that such KVM guest is not as easy to move to another host if current host can not boot. Copying image and config files will be much faster. Ljubomir ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
[CentOS] Slightly OT: First Time KVM and LVM on Centos
Greetings - I am a novice system administrator and will soon be purchasing a new server to replacing an aging file server for my company. I am considering setting up the new server as a KVM host with two guests; one guest as the Samba file server and a second guest as a testing area. My old server was set up about 7 years ago and has a 5 disk raid 5 configuration without LVM. I understand the benefits of using LVM and KVM in the right circumstances, but have never used either of them. I have spent a couple of days over the last week trying to understand how to setup a KVM host with guests, but there is an area that I still don't understand; that is the relationship between the underlying raid partitions, LVM, and allocating space to a host and guests. Many of the standard search term combinations in Google don't seem to be getting me anywhere. From what I have read so far I think that I want to have my file server guest using a raw partition rather than an image file, but I haven't found anything with examples or best-practices guidance for partitioning or volume management with hosts and guest VMs. So I am hoping that someone here can give me some pointers, or point me to some clear how-to's somewhere. Any help is appreciated. Thanks. Jeff Boyce Meridian Environmental www.meridianenv.com ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
Re: [CentOS] Slightly OT: First Time KVM and LVM on Centos
(...) I am hoping that someone here can give me some pointers, or point me to some clear how-to's somewhere. Any help is appreciated. Thanks Some good guides on virtualization and LVM reside here: https://access.redhat.com/knowledge/docs/Red_Hat_Enterprise_Linux/ vmware also has some very useful documentation: http://www.vmware.com/support/pubs/ ___ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos
