Re: [CentOS-virt] Why are bridges required?
Hi Lee If you are to virtualize the network stack properly you need to do it all the way down to layer2. How do you connect multiple layer 2 devices together? Well a bridge, a switch being many bridges all in the one box. Hubs are not relevant here as there is no physical medium. As the llya said it totally possible to have a 1:1 relationship between the vms and host, ie a dedicated bridge per vm, with its own ip network on (/30 for ipv4, or /64 for ipv6). The host machine then does all the routing and/or natting for the guests On 3 June 2014 04:06, Ilya Ponetayev inste...@gmail.com wrote: You may create as many bridges as you want to have virtual interfaces, each bridge consisting only of connection to single VM, and handle traffic between bridges and between physical interfaces of host through iptables/iproute. IHMO bridging is the most proper and popular technique because it provides the most flexible configuration. Your VM sees NIC as Ethernet card (so with all L2 features), so either you can terminate this L2 pipe with bridge in host, and perform L3/higher level handling, or you can use for example DHCP server on host binded to your bridge, or VLAN-handling config. On 03.06.2014 06:25, lee wrote: Hi, all the descriptions of networking setups with VMs I`m seeing involve bridges. The only use I see for bridges is when I actually want to be able to send network traffic to multiple arbitrary interfaces connected to the bridge. I do neither need, nor want bridges when I want to keep the VMs separated, like when separating a VM in a DMZ from a VM in the LAN. The bridge acts like a hub. Looking at [1] makes it seem that this is undesirable --- otherwise there wouldn`t be need for a software switch to prevent network traffic on a bridge from going to all of the connected interfaces. When there`s a bridge with multiple VMs connected to it, is a software switch desirable to prevent network traffic on the bridge from going to interfaces it doesn`t need to go to? If so, isn`t it better not to use a bridge to begin with? Can`t we simply have virtual interfaces on the physical host which are the other end of the interfaces showing up in the VMs, without bridges? [2] seems to suggest to leave all bridges dangling, i. e. it says you`re not supposed to connect an interface to the bridge. What`s the point of a bridge when only a single interface is connected to it? [1]: http://openvswitch.org/support/config-cookbooks/vlan- configuration-cookbook/ [2]: http://wiki.libvirt.org/page/Networking -- Sincerely yours, Ilya Ponetayev inste...@gmail.com ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] xen setup documentation for centos?
On Mon, Jun 2, 2014 at 1:45 AM, lee l...@yun.yagibdah.de wrote: Hi, what is the proposed way to create domU guests on centos 6.5? At first I tried to follow the documentation on the xen project website which recommends using xl. I created a config file and ended up with getting a message that the kernel is not bootable when trying to create a guest. I also had to stop some daemon (xend?) because it said that xl isn`t compatible with it and the daemon must be stopped first. I understand how frustrating it can be to be dealing with old / inaccurate documentation. But I'm not sure how we're supposed to help you if you don't give any details about what you did and exactly how it failed. If the instructions you followed don't work, then either: * You misunderstood something / accidentally left out a step / mistyped something from the documentation. * There's a bug in the CentOS implementation of Xen that needs to be fixed * There's a bug in the documentation that needs to be fixed If you describe which bit of documentation on the Xen website you tried to follow, what you were trying to do, and what happened, then we can figure out which of those it is and address the issue. The xend thing is an unfortunate -- as a project we're trying to move away from it, but there are still a large number of CentOS users who use it. Trying to make both new users and old users happy is a bit of a hard balancing act. -George ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] Xen DomU supoprt in RHEL 7 and the CentOS Plan
David Vrabel wrote on Tue, 27 May 2014 13:04:21 +0100: still do a text-console (in theory). Is this an interesting use case? It comes in handy for instance if there's something wrong with networking in the guest ;-) Also, I've used it in cases where the load was very high or when the VM was panicking or had some other problem that made it impossible to access via network. At least one get a glimpse on the last text console buffer and may guess what happened. So, yes, it's a valuable asset in emergency situations. Kai -- Get your web at Conactive Internet Services: http://www.conactive.com ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
Re: [CentOS-virt] [Hackathon] CentOS Virt SIG summary
Adding virt list, which we had missed off by mistake Lars On 03/06/2014 11:13, George Dunlap wrote: Sorry this is a bit sparse; I was both running the meeting and jotting down notes. Let me know if you have any questions. -George Present (from memory): - George Dunlap - Anil Madhavapeddy - Jonathan Ludlam - David Berrange - Dan Keningsberg - Dario Faggioli - [others I've forgotten] * Agenda - Package layout - ocaml - oVirt? - libvirt? - Sorting out check-in stuff * ocaml and xapi - Progess made yesterday in discussion with KB - RHEL 7 4.0.0.1 - xapi wants 4.0.1 - Depend on ocaml for *building* but not for *installing* * Packaging - xenstore client tools useful in domUs mixed in with libraries only useful in dom0 - How this would affect people upgrading? - obsoletes? - GWD to Mail JonL re virt sig repos * Build servers for SIGs? - koji up and running? - mock build environment - send it to Fedora first? - copr -- lightweight version of koji * oVirt - Must be in a separate repo for dependencies' sake - building more complicated (java, maven, c c) - Start with just copying RHEV * libvirt - No sense in making it a stable at this point - Use the lastest release until libxl support is fully featured / stabilized ___ CentOS-virt mailing list CentOS-virt@centos.org http://lists.centos.org/mailman/listinfo/centos-virt
[CentOS-virt] Log from today's IRC meeting (June 3rd, 2014)
With slight re-ordering to keep related things together kbsingh lars_kurth: Hi [13:52] kbsingh Are we doing this meeting on irc ? lars_kurth kbsingh: yes, we are [13:59] lars_kurth gwd: Hi. [14:02] lars_kurth Alright. I didn't put an agenda together gwd I've got a couple of things I wanted to bring up. [14:04] gwd Who else is here for the meeting? lars_kurth Please do. I think KB has some too jonludlam Hello lars_kurth gwd: seems we have jonludlam, kbsingh gwd and me so far [14:05] lars_kurth Hi. Before we properly start. Any changes on actions on http://wiki.centos.org/SpecialInterestGroup/Virtualization/Status ? lars_kurth So: no changes then? [14:06] gwd We chatted at the hackathon (with Daniel Barrange there) about libvirt versions jonludlam That was a good session [14:07] lars_kurth gwd: what was the outcome/recommendation? gwd What we said there was that libvirt/libxl driver isn't yet stable, so there's no point doing a choose a version and stick with it thing until it is. lars_kurth gwd: that is what I was afraid of [14:08] jonludlam so libvirt becomes a 'tech preview' until it stabilises? gwd Er, I don't think tech preview jonludlam 'unstable'? gwd More like, Not enterprise. :-) jonludlam ok pasik hello [14:09] jonludlam hi pasik gwd pasik: Hello gwd You know, like the kernel we want to be enterprise and only update every 2+ years. lars_kurth But that is only an issue for libxl, mot xm. Correct? If we are still talking Xen 4.4 that should not be an issue gwd I don't think we want to encourage anyone to use xend if we can possibly help it. gwd We need to transition people away from it. [14:10] jonludlam libvirt is a reasonable transition strategy though gwd Is there a need for enterprise libvirt? Is anyone using that? pasik Hopefully we can get thinks into better shape with xen 4.4 + later libvirt lars_kurth Agreed. How about the needs of KVM, oVirt, ... for libvirt pasik with the current xen 4.2 packages basicly only xend is usable (with libvirt) gwd pasik / euanh: We were just talking about how often to update the libvirt packages. jonludlam ovirt will take a good deal of porting to work with xen lars_kurth jonludlam: correct. But this SIG is not about Xen only [14:11] jonludlam true, but gwd jonludlam: given how much hypervisor detail is exposed by libvirt, how reliable would a libvirt/xend - libvirt/libxl transition go? jonludlam What was said was that ovirt effectively doesn't need anything provided by what we're looking at in sig virt today [14:12] jonludlam gwd, I don't think it would be too bad - it already autodetects whether to use xl or xm based on what's installed, if you connect to xen:// gwd lars_kurth: I think if someone wants to use oVirt+KVM, they can use the core libvirt. gwd jonludlam: Sure, but as we found out, libvirt doesn't try very hard to hide the hypervisor details. [14:13] jonludlam qemu was mentioned in the meeting at the hackathon, but it's totally orthogonal to everything else in the SIG so far jonludlam gwd, but the difference between libxl and xend is much smaller than between qemu and xen gwd Sure; but it may still be a fairly major headache to get stuff to work. lars_kurth kbsingh: any views? I thought you were worried about scope creep in the SIG. lars_kurth Sorry: SIG [14:14] gwd And what actually works well with libvirt+xen at the moment anyway? xm/xl are better than virsh, IMHO lars_kurth gwd: That is probably correct. On the other hand, we don't have an interface into Cloud SIGs until we have libvirt and/or xapi jonludlam the xapi question was a bit clearer after the meetings. Anil and KB talked about an OCaml SIG that the virt SIG could gwd lars_kurth: Yes, but those are not going to be enterprisey either. :-) lars_kurth gwd: so what is the proposal gwd The proprosals are: depend on gwd 1) Choose a version of libvirt (1.2.3 maybe) and stick with it, backporting functionality we're missing. [14:16] gwd 2) Update the libvirt package when there's a new libvirt release until libxl support is mature enough pasik gwd: I use virt-install often to install new VMs pasik gwd: imho it's the easiest way to launch $distro installers in a PV domU [14:17] gwd #2 is easier for us, and will get us all the available libvirt/xen functionality; it's what we favored at the metting at the hackathon. pasik gwd: and virt-install works with xen4.2+xend+libvirt in el6 gwd The only downside is that enterprise customers don't like such frequent updates. jonludlam Daniel B said that #1 would be tricky, as they were refactoring the other bits of libvirt to make the xl plugin easier [14:18] DV We really try to not break libvirt upstream, ideally having the git version run for regtests on libxl would be a good idea gwd DV: Upstream Xen Project already does that. DV * DV agrees with danpb , even in RHEL we rebase to try to avoid backporting gwd Having a new libvirt shouldn't *interfere* with oVirt, virt-install, cc. [14:19] DV gwd: ah, good,
[CentOS-virt] Meeting bot (was Re: Log from today's IRC meeting (June 3rd, 2014))
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Side-topic (and subject changed), but do we have centbot running in this channel? I'd love to get us in the habit of using Meetbot, it makes for such nice meeting minutes and logs. Can I offer to join all meetings happening for the next little while and run the bot to show how the flow works? (I can also moderate any IRC meeting that folks want, so all of you can be participants; it can be hard to moderate IRC and also discuss.) Anyone who wants that help etc. you can invite me to your meeting, karstenw...@gmail.com is my calendar. Thanks - Karsten On 06/03/2014 10:06 AM, Lars Kurth wrote: With slight re-ordering to keep related things together kbsingh lars_kurth: Hi [13:52] kbsingh Are we doing this meeting on irc ? lars_kurth kbsingh: yes, we are [13:59] lars_kurth gwd: Hi. [14:02] lars_kurth Alright. I didn't put an agenda together gwd I've got a couple of things I wanted to bring up. [14:04] gwd Who else is here for the meeting? lars_kurth Please do. I think KB has some too jonludlam Hello lars_kurth gwd: seems we have jonludlam, kbsingh gwd and me so far [14:05] lars_kurth Hi. Before we properly start. Any changes on actions on http://wiki.centos.org/SpecialInterestGroup/Virtualization/Status ? lars_kurth So: no changes then? [14:06] gwd We chatted at the hackathon (with Daniel Barrange there) about libvirt versions jonludlam That was a good session [14:07] lars_kurth gwd: what was the outcome/recommendation? gwd What we said there was that libvirt/libxl driver isn't yet stable, so there's no point doing a choose a version and stick with it thing until it is. lars_kurth gwd: that is what I was afraid of [14:08] jonludlam so libvirt becomes a 'tech preview' until it stabilises? gwd Er, I don't think tech preview jonludlam 'unstable'? gwd More like, Not enterprise. :-) jonludlam ok pasik hello [14:09] jonludlam hi pasik gwd pasik: Hello gwd You know, like the kernel we want to be enterprise and only update every 2+ years. lars_kurth But that is only an issue for libxl, mot xm. Correct? If we are still talking Xen 4.4 that should not be an issue gwd I don't think we want to encourage anyone to use xend if we can possibly help it. gwd We need to transition people away from it. [14:10] jonludlam libvirt is a reasonable transition strategy though gwd Is there a need for enterprise libvirt? Is anyone using that? pasik Hopefully we can get thinks into better shape with xen 4.4 + later libvirt lars_kurth Agreed. How about the needs of KVM, oVirt, ... for libvirt pasik with the current xen 4.2 packages basicly only xend is usable (with libvirt) gwd pasik / euanh: We were just talking about how often to update the libvirt packages. jonludlam ovirt will take a good deal of porting to work with xen lars_kurth jonludlam: correct. But this SIG is not about Xen only [14:11] jonludlam true, but gwd jonludlam: given how much hypervisor detail is exposed by libvirt, how reliable would a libvirt/xend - libvirt/libxl transition go? jonludlam What was said was that ovirt effectively doesn't need anything provided by what we're looking at in sig virt today [14:12] jonludlam gwd, I don't think it would be too bad - it already autodetects whether to use xl or xm based on what's installed, if you connect to xen:// gwd lars_kurth: I think if someone wants to use oVirt+KVM, they can use the core libvirt. gwd jonludlam: Sure, but as we found out, libvirt doesn't try very hard to hide the hypervisor details. [14:13] jonludlam qemu was mentioned in the meeting at the hackathon, but it's totally orthogonal to everything else in the SIG so far jonludlam gwd, but the difference between libxl and xend is much smaller than between qemu and xen gwd Sure; but it may still be a fairly major headache to get stuff to work. lars_kurth kbsingh: any views? I thought you were worried about scope creep in the SIG. lars_kurth Sorry: SIG [14:14] gwd And what actually works well with libvirt+xen at the moment anyway? xm/xl are better than virsh, IMHO lars_kurth gwd: That is probably correct. On the other hand, we don't have an interface into Cloud SIGs until we have libvirt and/or xapi jonludlam the xapi question was a bit clearer after the meetings. Anil and KB talked about an OCaml SIG that the virt SIG could gwd lars_kurth: Yes, but those are not going to be enterprisey either. :-) lars_kurth gwd: so what is the proposal gwd The proprosals are: depend on gwd 1) Choose a version of libvirt (1.2.3 maybe) and stick with it, backporting functionality we're missing. [14:16] gwd 2) Update the libvirt package when there's a new libvirt release until libxl support is mature enough pasik gwd: I use virt-install often to install new VMs pasik gwd: imho it's the easiest way to launch $distro installers in a PV domU [14:17] gwd #2 is easier for us, and will get us all the available libvirt/xen functionality;
