virt November 2011

virt@lists.centos.org

13 participants
12 discussions

centos6 and xen4 dom0 memory allocation
by Peter Peltonen 08 Jul '12

08 Jul '12

Hi, This is slightly OT as xen is not officially supported in EL6. But maybe someone else is running it on centos6 as well and could help me out here: I have problems allocating a static amount of memory for my xen dom0. It seems to reduce when new domUs are created, even though I *think* ballooning is disabled. Can someone advise me what I'm doing wrong? I have xen-4.1.1-3 installed from http://xenbits.xen.org/people/mayoung/EL6.xen on my centos6 server. I am running 2.6.32-131.12.1.el6.xendom0.x86_64 kernel available from the same place. 'xl info' reports about available memory as follows: total_memory : 24567 free_memory : 3698 xen_commandline : dom0_mem=2048M and in xend-config.sxp I have: (dom0-min-mem 256) (enable-dom0-ballooning no) (total_available_memory 0) Now one would think that I should have 2048M memory for dom0, right? I started from there, but when starting domUs it has been reduced to 1140M even though I think ballooning is disabled and there is free memory available? And the weird thing is that dom0 has done some swapping: # free -mt total used free shared buffers cached Mem: 1140 1052 88 0 2 12 -/+ buffers/cache: 1038 102 Swap: 8194 85 8109 Total: 9335 1138 8197 Shutting down domUs and making more memory available does not reverse the effect, dom0 does not allocate more memory. What am I missing here or is my xen setup acting strangely here? Best regards, Peter

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Transfer of LVM based guests
by James B. Byrne 30 Nov '11

30 Nov '11

I am investigating the procedure to follow when moving a KVM guest instance from one host to another where the guest uses LVM as its storage. As a preliminary cut I have cobbled the following together from various sources located through Google searches: 1. Log in to vmhost_old 2. Shutdown guest 3. Create an LVM snapshot of the guest volume 3.a. lvcreate -s -L 300m -n LVM_guest_snapshot guest_lv 4. Convert snapshot to a file image 4.a dd if=/dev/vhost/LVM_guest_snapshot of=/tmp/fs/LVM_guest_snapshot.img bs=4096 5. Remove the original snapshot 5.a lvremove /dev/vhost/LVM_guest_snapshot 6. Move the snapshot image file to the new KVM host. Note that for large vm guest images tape transport is probably better than network transfers. 7. Log in to vhost_new 8. Create a new lv on the new vhost 8.a lvcreate -n guest_name_lv -L 60G vhost_new_vg 9. Copy transferred image to new LV 9.a dd if=tmp/LVM_guest_snapshot.img of=/dev/vhost_new/guest_name_lv bs=4096 10. Copy guest xml file from vhost_old via sftp 10.a. get /etc/libvirt/qemu/guest_name.xml \ /etc/libvirt/qemu/guest_name.xml 11. Start new guest? Is there anything obviously wrong or omitted from this? -- *** E-Mail is NOT a SECURE channel *** James B. Byrne mailto:ByrneJB@Harte-Lyne.ca Harte & Lyne Limited http://www.harte-lyne.ca 9 Brockley Drive vox: +1 905 561 1241 Hamilton, Ontario fax: +1 905 561 0757 Canada L8E 3C3

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kvm: w7 bsod's at shutdown
by Todd And Margo Chester 28 Nov '11

28 Nov '11

Hi All, I am using Scientific Linux 6.1 x64 Any idea how to get my W7 x32 guest to shutdown with out a BSOD? I have to go into virt-manager and kill it all the time. My XP guest shuts down without issue. Many thanks, -T $ rpm -qa \*kvm\* qemu-kvm-0.12.1.2-2.160.el6_1.2.x86_64 $ rpm -qa \*virt\* python-virtinst-0.500.5-3.el6.noarch libvirt-0.8.7-18.el6_1.1.x86_64 libvirt-client-0.8.7-18.el6_1.1.x86_64 virt-manager-0.8.6-4.el6.noarch libvirt-python-0.8.7-18.el6_1.1.x86_64

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Device renaming heads up
by Karanbir Singh 26 Nov '11

26 Nov '11

hi Guys, Just in case anyone hasent noticed this : https://bugzilla.redhat.com/show_bug.cgi?id=729586 device naming mixup causing lots of domU's to not come back after a kernel update... - KB

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XEN multiple bridge problem - VM won' start!
by Matija Draganović 25 Nov '11

25 Nov '11

Finally, I managed to solve the problem. The problem was rather strange - after configuring bridges I added new ifaces to the VM. For some reason, during boot process of the VM's, wrong interface was started (VM tried to bring up eth2 instead eth1?). After adding the new ifaces through virt-manager, the VM started regulary and created a new network script for eth2 (/etc/sysconfig/network-scripts/ifcfg-eth2). I think that the problem was this - when the VM is restarted it tried to bring up eth2 while vif-script tried to propagate second bridge via eth1 iface. I resolved this simply by replacing ifcfg-eth2 script with ifcfg-eth1. Now, VM starts/restarts regulary ;) So, the process for creating and configuring new bridges that I follow is (tried on multiple servers): - create new script that sets up multiple bridges in /etc/xen/scripts/ example: network-xen-multi-bridge #!/bin/sh # network-xen-multi-bridge # Exit if anything goes wrong. set -e # First arg is the operation. OP=$1 shift script=/etc/xen/scripts/network-bridge.xen case ${OP} in start) $script start vifnum=3 bridge=xenbr3 netdev=eth3 $script start vifnum=0 bridge=xenbr0 netdev=eth0 ;; stop) $script stop vifnum=3 bridge=xenbr3 netdev=eth3 $script stop vifnum=0 bridge=xenbr0 netdev=eth0 ;; status) $script status vifnum=3 bridge=xenbr3 netdev=eth3 $script status vifnum=0 bridge=xenbr0 netdev=eth0 ;; *) echo 'Unknown command: ' ${OP} echo 'Valid commands are: start, stop, status' exit 1 esac - make it executable (chmod 755 network-xen-multi-bridge) - configure /etc/xen/xend-config.sxp (comment out the current script and add the new one); # It is possible to use the network-bridge script in more complicated # scenarios, such as having two outgoing interfaces, with two bridges, and # two fake interfaces per guest domain. To do things like this, write # yourself a wrapper script, and call network-bridge from it, as appropriate. # #(network-script network-bridge) (network-script network-xen-multi-bridge) - restart physical server so the bridges are properly created - add virt. ifaces to the VM's (via virt-manager or via config. files in /etc/xen/ ..) - boot VM - configure newly added iface in /etc/sysconfig/network-scripts/ - restart VM Additionaly I check everything by restarting phys. server to make sure that everything is ok ;)

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Bonds, VLANs, and Bridges on Centos 5.6
by Jason Nagashima 23 Nov '11

23 Nov '11

Running on Centos 5.6 with KVM... I was wondering if anyone had any luck configuring the NICs where eth0 and eth1 are bonded together with vlan support to a bridge? I noticed some threads show this as a possibility (http://lists.centos.org/pipermail/centos-virt/2009-November/001417.html), but haven't had any luck implementing it. There also seems to be a bug with 5.6 (http://bugs.centos.org/view.php?id=4801), but that post died the day it was created it. Any advice/working examples would be greatly appreciated. Regards, Jason

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XEN multiple bridge problem - VM won' start!
by Matija Draganović 22 Nov '11

22 Nov '11

Ok, after trying multiple different configurations I decided to play by the book - I removed ifcfg script for creating the additional bridge and set up an Xen script. So my new configuration is: -> eth3 (my physical interface) # NetXen Incorporated NX3031 Multifunction 1/10-Gigabit Server Adapter DEVICE=eth3 BOOTPROTO=static HWADDR= ... ONBOOT=yes IPADDR= ... NETMASK= ... NETWORK= ... and the network-xen-multi-bridge script: #!/bin/sh # network-xen-multi-bridge # Exit if anything goes wrong. set -e # First arg is the operation. OP=$1 shift script=/etc/xen/scripts/network-bridge.xen case ${OP} in start) $script start vifnum=3 bridge=xenbr3 netdev=eth3 $script start vifnum=0 bridge=xenbr0 netdev=eth0 ;; stop) $script stop vifnum=3 bridge=xenbr3 netdev=eth3 $script stop vifnum=0 bridge=xenbr0 netdev=eth0 ;; status) $script status vifnum=3 bridge=xenbr3 netdev=eth3 $script status vifnum=0 bridge=xenbr0 netdev=eth0 ;; *) echo 'Unknown command: ' ${OP} echo 'Valid commands are: start, stop, status' exit 1 esac After I restart the physical server bridges are set up correctly: # brctl show bridge name bridge id STP enabled interfaces virbr0 8000.000000000000 yes xenbr0 8000.feffffffffff no vif0.0 peth0 xenbr3 8000.feffffffffff no vif0.3 peth3 Unfortunately, this did not solve the problem - I manage to start one VM (connected to both of the bridges), but when I try to start the other one, it just hangs when trying to bring up the second interface (connected to xenbr3) :/ I'm currently completely out of ideas, but I'm not giving up ;)

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XEN multiple bridge problem - VM won' start!
by Matija Draganović 19 Nov '11

19 Nov '11

I tried to remove vifname and vif-script but the problem remains. I think that the bridges are ok, but for some reason VM's hang when they try to connect their vifaces to them. I'll try some different configurations of the physical ifaces (an vifaces also), maybe I'll be able to find out something. Also, I'll focus on the vTPM, since the following line shows up in the Xen log when the VM tries to bring up the iface connected to the second bridge: [2011-11-18 09:27:16 xend 8213] DEBUG (DevController:160) Waiting for devices vtpm Furthermore, it appears that sometimes the VM's manage to start regulary, I just can't figure out when & why :/ Tnx for your comments .. Br, M.

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high resolution video for kvm vm
by Nataraj 19 Nov '11

19 Nov '11

I'm running a fuduntu vm (based on fedora 14) on a CentOS 6 kvm server. I have tried changing the video in virt-manager from cirrus to vga and restarting the VM, but the maximum resolution that the client will let me set is still only 1024x768. Should I be able to get high res video with the kvm VGA mode? Note that the VM is running on a CentOS server while virt-manager is running on my local desktop. Would I be better off trying to get the vmware VGA driver working? I'm assuming I have to extract the driver from the vmware tools package and manually install it into the X server, because VMware tools won't install under kvm. Also, I run with the keyboard option to swap caps lock and control on my linux desktop, which does not seem to get passed through to the guest. I tried setting the same swap caps lock and control option in the guest, but it does not work. Any ideas? Thanks, Nataraj

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XEN multiple bridge problem - VM won' start!
by Matija Draganović 18 Nov '11

18 Nov '11

Dear Peter, Thanks for your reply. I was so occupied with troubleshooting that I forgot to mention the OS & Xen version :) My CentOS version is CentOS release 5.7 (Final) Linux 2.6.18-274.7.1.el5xen #1 SMP Thu Oct 20 17:06:34 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux and Xen v3.0. I tried creating bridges the same way you did and succedded. I also tried doing the same via ifcfg scripts, and it also worked. I have no problem with creating bridges and connecting them with physical ifaces, but I can't start my VM's (most of the time one VM start but the other one hangs while trying to initalize eth2 that is connected to my second (non default - xenbr1) bridge)). The only diference between your config and mine is that I have vifname-s listed (example below): vif = [ "mac=00:16:36:72:35:e5,bridge=xenbr0,script=vif-bridge,vifname=vif4.0", "mac=00:16:3e:57:de:0d,bridge=xenbr1,script=vif-bridge, vifname=vif4.1" ] I'm not saying that this could be the problem, but since I'm slowly running out of ideas - it's a longshot :) So, to sum it all up - I can create bridges properly, but my VM's hang when they try to bring up vifaces connected to the xenbr1. Also, I have no problem with having only one bridge active - problem appears when I have multiple bridges. Br, Matija

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virt November 2011