virt February 2012

virt@lists.centos.org

19 participants
22 discussions

Has anyone been able to start a Fedora 16 VM in Xen PV?
by Scot P. Floess 09 Jul '12

09 Jul '12

All, I've had a heck of a time getting Fedora 16 to run as a guest VM under CentOS 5.7 host as a paravirtualized Xen guest. I believe the issue has something to do with Fedora 16 using grub2... When I attempt to start the VM (via xm create), I get this error: Using config file "/etc/xen/fedora-workstation". Traceback (most recent call last): File "/usr/bin/pygrub", line 686, in ? fs = fsimage.open(file, get_fs_offset(file)) IOError: [Errno 95] Operation not supported No handlers could be found for logger "xend" Error: Boot loader didn't return any data! In my kickstart, I had to create a partition for F16 as: part biosboot --fstype=biosboot --size=1 I didn't readily find the error when googling... Has anyone been able to run F16 as a PV guest? And if so, what did you do to make it happen????? Thanks!!!!!!!!!!!!! Scot P. Floess RHCT (Certificate Number 605010084735240) Chief Architect FlossWare http://sourceforge.net/projects/flossware http://flossware.sourceforge.net https://github.com/organizations/FlossWare

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centos6 and xen4 dom0 memory allocation
by Peter Peltonen 09 Jul '12

09 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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New Tutorial - RHCS + DRBD + KVM; 2-Node HA on EL6
by Digimer 19 Jun '12

19 Jun '12

Hi all, I'm happy to announce a new tutorial! https://alteeve.com/w/2-Node_Red_Hat_KVM_Cluster_Tutorial This tutorial walks a user through the entire process of building a 2-Node cluster for making KVM virtual machines highly available. It uses Red Hat Cluster services v3 and DRBD 8.3.12. It is written such that you can use entirely free or fully Red Hat supported environments. Highlights; * Full network and power redundancy; no single-points of failure. * All off-the-shelf hardware; Storage via DRBD. * Starts with base OS install, no clustering experience required. * All software components explained. * Includes all testing steps covered. * Configuration is used in production environments! This tutorial is totally free (no ads, no registration) and released under the Creative Common 3.0 Share-Alike Non-Commercial license. Feedback is always appreciated! -- Digimer E-Mail: digimer(a)alteeve.com Freenode handle: digimer Papers and Projects: http://alteeve.com Node Assassin: http://nodeassassin.org "omg my singularity battery is dead again. stupid hawking radiation." - epitron

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Guests pausing suddenly
by Peter Hopfgartner 27 Apr '12

27 Apr '12

We have a CentOS 6.2 server with KVM. That server hosts 2 virtual machines, both with Centos 6.2, too. Regularly, one or both of the virtual machines pass to state "pause" without apparent reason. On resume, I do get have messages, like the following in /var/log/messages. Feb 28 21:50:45 achernar fcoemon: Failed to connect to lldpad Feb 29 08:23:56 achernar kernel: sd 0:0:0:0: [sda] Unhandled error code Feb 29 08:23:56 achernar kernel: sd 0:0:0:0: [sda] Result: hostbyte=DID_OK driverbyte=DRIVER_TIMEOUT Feb 29 08:23:56 achernar kernel: sd 0:0:0:0: [sda] CDB: Write(10): 2a 00 06 db 70 78 00 00 38 00 Feb 29 08:23:56 achernar kernel: end_request: I/O error, dev sda, sector 115044472 Feb 29 08:23:56 achernar kernel: Buffer I/O error on device dm-0, logical block 14252047 Feb 29 08:23:56 achernar kernel: lost page write due to I/O error on dm-0 Feb 29 08:23:56 achernar kernel: Buffer I/O error on device dm-0, logical block 14252048 Feb 29 08:23:56 achernar kernel: lost page write due to I/O error on dm-0 Feb 29 08:23:56 achernar kernel: Buffer I/O error on device dm-0, logical block 14252049 Feb 29 08:23:56 achernar kernel: lost page write due to I/O error on dm-0 Feb 29 08:23:56 achernar kernel: Buffer I/O error on device dm-0, logical block 14252050 Feb 29 08:23:56 achernar kernel: lost page write due to I/O error on dm-0 Feb 29 08:23:56 achernar kernel: Buffer I/O error on device dm-0, logical block 14252051 Feb 29 08:23:56 achernar kernel: lost page write due to I/O error on dm-0 Feb 29 08:23:56 achernar kernel: Buffer I/O error on device dm-0, logical block 14252052 Feb 29 08:23:56 achernar kernel: lost page write due to I/O error on dm-0 Feb 29 08:23:56 achernar kernel: Buffer I/O error on device dm-0, logical block 14252053 Feb 29 08:23:56 achernar kernel: lost page write due to I/O error on dm-0 Feb 29 08:23:57 achernar fcoemon: error 111 Connection refused I could not find any sensible message on the pysical host, neither in /var/log/messages nor in /var/log/libvirt. We do have an almost identical server, same hardware, same software which does not have this problem. How could I proceed to better diagnose the cause of the troubles? Regards, -- Peter Hopfgartner web : www.r3-gis.com

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Re: [CentOS-virt] Resize guest filesystem question
by Jeff Boyce 28 Feb '12

28 Feb '12

Responding to the daily digest, see comment at bottom. > Message: 1 > Date: Mon, 27 Feb 2012 14:01:27 +0100 > From: Markus Falb <markus.falb(a)fasel.at> > Subject: Re: [CentOS-virt] Resize guest filesystem question > To: centos-virt(a)centos.org > Message-ID: <jifur8$pmi$1(a)dough.gmane.org> > Content-Type: text/plain; charset="iso-8859-1" > > On 24.2.2012 21:28, Sergiy Yegorov wrote: >> Fri, 24-Feb-2012 12:05:55 Jeff Boyce wrote: >> >>> 6. Then I ran resize2fs /dev/vda2 and got the result that the >>> filesystem >>> is already xx blocks long. Nothing to do! >> Before you can resize filesystem, you have to resize partition. >> If it is only 2 partitions on /dev/vda, you can use one of two ways: >> 1. Resize partition from host system (I think it is not the best idea for >> root >> partition operations): >> Run fdisk /dev/vg/lv_guest1root, delete second partition and create new >> one >> which starts from the same place but takes all available space, after it >> you >> can boot guest (in single mode) and run resize2fs. >> 2. Boot VM from any 3-party (LiveCD or any) with access to virtual disk, >> and >> do the same: in fdisk delete existing partition, create new one and run >> resize2fs on it. Or just use parted to do it in one command. > > 3. You can repartition from the guest itself > Do as in 2. After saving the new partition table fdisk will probably > request a reboot for using the new table. reboot, then resize the fs. > > -- > Kind Regards, Markus Falb > Thanks to everyone that replied. Ed gave me the right clue that I was missing (and is apparently missing in a lot of the how-to's that I reviewed which only said to expand the LV, then expand the filesystem). I had to expand the partition before expanding the filesystem. So for my solution I rebooted that particular VM using SystemRescue LiveCD, then started GParted and expanded the partition which also expanded the filesystem in a single step. Then rebooted using the VM's image and #df -h now shows the expanded LV and a file system on the full space. Jeff

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Resize guest filesystem question
by Jeff Boyce 27 Feb '12

27 Feb '12

Greetings - I am going through some testing steps to expand a logical volume and the corresponding filesystem on a KVM guest and have run across a deficiency in my knowledge. I spent the afternoon yesterday googling for answers, but had have come up blank still. What I am trying to do is resize the file system to use the additional disk space that I added to the logical volume that the guest uses. Here is what I have done and the details of my system. 0. Both my host and guest are running Centos 6.2. 1. My KVM host system has the LVM volume group that is divided into logical volumes which are then presented to the KVM guests as raw space. 2. A guest may use 2 or 3 logical volumes from the host system for its filesystem (/, /var, /data) and I have logical volumes named within the host system by guest and mount point so that I know what each logical volume is assigned to by it's name. 3. I expanded a specific logical volume on the host (/dev/vg/lv_guest1root) that is used by Guest1, and I can see in vgdisplay and lvdisplay that the logical volume was properly expanded. 4. I then issued a resize2fs /dev/vg/lv_guest1root command (on the host) to resize the filesystem to the expanded logical volume. This resulted in a message that it essentially couldn't find a valid filesystem superblock. Well of course then I realized that there is no filesystem on the logical volume from the perspective of the host. The filesystem wasn't set on the logical volume until the guest installation occurred. 5. So then I switched over to the guest system and ran df -h to see the existing filesystem [root@guest1 jeffb]# df -h Filesystem Size Used Avail Use% Mounted on /dev/vda2 4.5G 2.3G 2.0G 53% / tmpfs 1004M 88K 1004M 1% /dev/shm /dev/vda1 485M 30M 430M 7% /boot /dev/vdb1 2.0G 219M 1.7G 12% /var 6. Then I ran resize2fs /dev/vda2 and got the result that the filesystem is already xx blocks long. Nothing to do! So here is where I am stuck. Guest1 is my test system so it only has the / and /var logical volumes, whereas the production guest (guest2) that I will be expanding also has /data, which will be the logical volume that I will expand. So two things I did not do where, I did not shut down the guest VM, and I did not unmount the filesystem before asking it to resize. However my research before doing this did not seem to indicate that I had to do either, and the message about nothing to do also seems to indicate that they were not necessary. So I am missing a hole in my knowledge and additional googling has not helped to fill it. I must be missing something simple. Is this result due to the fact that I am testing on expanding the / filesystem, and it would work properly on a guest system that had /data? Do I need to unmount the filesystem, or shut down the guest VM, or mount the guest from a LiveCD? Or do I need to give it resize2fs /dev/vda rather than specifically /dev/vda2 ? Any clues, or pointers to good documentation is greatly appreciated. Thanks. Jeff Boyce Meridian Environmental www.meridianenv.com

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Re: [CentOS-virt] How many virtual guest 'cpus' can a core duo 'quad' core support
by James B. Byrne 25 Feb '12

25 Feb '12

On Wed, February 22, 2012 12:25, Todd And Margo Chester > > Therefore, in your given case, think six not twelve. > Common advice is > to leave > one core for the host OS/scheduler. Which leaves you with > 5 physical > CPUs to > allocate. > Thank you. I never planned to allocate to any guest more cpus that were physically available. What I was checking was that a single physical cpu with four cores actually counted as four cpus insofar as kvm itself was concerned. I have allocated guests their processors on the basis that 1 core = 1 cpu. But it occurred to me that core might actually mean something different and so I wanted to verify my understanding. -- *** 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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SELinux killed my qemu-kvm
by David McGuffey 25 Feb '12

25 Feb '12

All of a sudden, Virtual Machine Manager (VMM) on a CentOS 5.7 load will no longer run any VMs. The VM worked A-OK on the morning of 23 Feb, when I brought it up, applied the Microsoft updates, rebooted it, installed an application, rebooted again and ran several tests. Later that day, it wouldn't run. I didn't have time to diagnose, so I did some investigation a few minutes ago. Working my way through some checks, it appears to be an SELinux problem (new). [root@desk log]# uname -r 2.6.18-274.18.1.el5 >From /var/log/yum.log: Feb 21 19:07:01 Updated: 2:libpng-1.2.10-15.el5_7.x86_64 Feb 21 19:07:01 Updated: 2:libpng-devel-1.2.10-15.el5_7.x86_64 Feb 21 19:07:01 Updated: 2:libpng-1.2.10-15.el5_7.i386 Previous yum update ran on 19 Feb. However, the virtual machine ran very well on the morning of 23 Feb, when I brought it up, so it can't be any updates from yum on the host. Here is the VMM Error Message: Error starting domain: internal error Process exited while reading console log output: qemu: could not open disk image /dev/hda And the VMM Details: Traceback (most recent call last): File "/usr/share/virt-manager/virtManager/engine.py", line 501, in run_domain vm.startup() File "/usr/share/virt-manager/virtManager/domain.py", line 576, in startup self.vm.create() File "/usr/lib64/python2.4/site-packages/libvirt.py", line 333, in create if ret == -1: raise libvirtError ('virDomainCreate() failed', dom=self) libvirtError: internal error Process exited while reading console log output: qemu: could not open disk image /dev/hda Excerpt from /var/log/messages: Feb 24 17:25:28 desk libvirtd: 17:25:28.531: error : virDomainDiskDefForeachPath:7637 : unable to open disk path /dev/hda: No medium found Feb 24 17:25:28 desk kernel: tun: Universal TUN/TAP device driver, 1.6 Feb 24 17:25:28 desk kernel: tun: (C) 1999-2004 Max Krasnyansky <maxk(a)qualcomm.com> Feb 24 17:25:28 desk kernel: device vnet0 entered promiscuous mode Feb 24 17:25:28 desk kernel: New device vnet0 does not support netpoll Feb 24 17:25:28 desk kernel: Disabling netpoll for virbr0 Feb 24 17:25:28 desk kernel: virbr0: topology change detected, propagating Feb 24 17:25:28 desk kernel: virbr0: port 1(vnet0) entering forwarding state Feb 24 17:25:28 desk kernel: virbr0: port 1(vnet0) entering disabled state Feb 24 17:25:28 desk kernel: virbr0: port 1(vnet0) entering disabled state Feb 24 17:25:28 desk kernel: device vnet0 left promiscuous mode Feb 24 17:25:28 desk kernel: virbr0: port 1(vnet0) entering disabled state Feb 24 17:25:28 desk setroubleshoot: SELinux is preventing pam_console_app (pam_console_t) "getattr" to /dev/hda (virt_content_t). For complete SELinux messages. run sealert -l 9ee6c9a9-3eda-4082-84d3-5741ea9ff688 SELinux alert summary SELinux is preventing pam_console_app (pam_console_t) "getattr" to /dev/hda (virt_content_t). Detailed Description: SELinux denied access requested by pam_console_app. It is not expected that this access is required by pam_console_app and this access may signal an intrusion attempt. It is also possible that the specific version or configuration of the application is causing it to require additional access. Allowing Access: Sometimes labeling problems can cause SELinux denials. You could try to restore the default system file context for /dev/hda, restorecon -v '/dev/hda' If this does not work, there is currently no automatic way to allow this access. Instead, you can generate a local policy module to allow this access - see FAQ (http://fedora.redhat.com/docs/selinux-faq-fc5/#id2961385) Or you can disable SELinux protection altogether. Disabling SELinux protection is not recommended. Please file a bug report (http://bugzilla.redhat.com/bugzilla/enter_bug.cgi) against this package. Additional Information: Source Context system_u:system_r:pam_console_t:SystemLow- SystemHigh Target Context system_u:object_r:virt_content_t Target Objects /dev/hda [ blk_file ] Source pam_console_app Source Path /sbin/pam_console_apply Port <Unknown> Host desk.mcguffeyfamily.net Source RPM Packages internallab pam-0.99.6.2-6.el5_5.2 Target RPM Packages Policy RPM selinux-policy-2.4.6-316.el5_7.1 Selinux Enabled True Policy Type targeted MLS Enabled True Enforcing Mode Enforcing Plugin Name catchall_file Host Name desk.mcguffeyfamily.net Platform Linux desk.mcguffeyfamily.net 2.6.18-274.18.1.el5 #1 SMP Thu Feb 9 12:45:44 EST 2012 x86_64 x86_64 Alert Count 163 First Seen Wed 13 Apr 2011 08:41:32 AM EDT Last Seen Fri 24 Feb 2012 05:25:28 PM EST Local ID 9ee6c9a9-3eda-4082-84d3-5741ea9ff688 Line Numbers Raw Audit Messages host=desk.internallab.net type=AVC msg=audit(1330122328.766:39): avc: denied { getattr } for pid=3427 comm="pam_console_app" path="/dev/hda" dev=tmpfs ino=6316 scontext=system_u:system_r:pam_console_t:s0-s0:c0.c1023 tcontext=system_u:object_r:virt_content_t:s0 tclass=blk_file host=desk.internallab.net type=SYSCALL msg=audit(1330122328.766:39): arch=c000003e syscall=4 success=no exit=-13 a0=7fff56fe6140 a1=7fff56fe6170 a2=7fff56fe6170 a3=c5df105 items=0 ppid=3417 pid=3427 auid=4294967295 uid=0 gid=0 euid=0 suid=0 fsuid=0 egid=0 sgid=0 fsgid=0 tty=(none) ses=4294967295 comm="pam_console_app" exe="/sbin/pam_console_apply" subj=system_u:system_r:pam_console_t:s0-s0:c0.c1023 key=(null) I did a touch /.autorelabel; sync; reboot and received the same error message. I then followed the guidance in the sealert: [root@desk log]# restorecon -v /dev/hda restorecon reset /dev/hda context system_u:object_r:virt_content_t:s0->system_u:object_r:fixed_disk_device_t:s0 And tried to start the VM with no success: [root@desk images]# virsh start Win7-base error: Failed to start domain Win7-base error: internal error Process exited while reading console log output: qemu: could not open disk image /dev/hda Any thoughts? Dave

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new libvirt: CentOS 6.2 versus 6.0
by Dmitry E. Mikhailov 23 Feb '12

23 Feb '12

Hi, About half a year ago I installed a stock CentOS 6.0/64bit onto an Intel server to virtualize our Linux fileserver and four WinXP boxes with rdp each. Since recent times I didn't do any upgrades of the server's OS. Now I have CentOS 6.2. After an upgrade I noticed that all virtual cpu name changed to QEMU Virtual CPU version (cpu64-rhel6) The new features were 1) The ability to specify cpu type and even exact capabilities 2) The ability to set the topology. It's good because before this ability appears WinXP guests won't use more than two cores. I got problem with both of these features. First, I can't manually specify cpu type 'qemu64' - virtmanager says my physical CPU doesn't have some abilities. But if no CPU is specified, it is reported as 64bit Second, a killer app on one of WinXP servers stopped working since upgrade. It's a russian proprietary accounting app named 1C ver. 8.1 (1cv8.exe). It would just hang loading single virtual CPU to 100%. I traced by trial-and-error that the problem is related to virtual CPU identification. Following solution would help: <cpu match='exact'> <model>Penryn</model> <vendor>Intel</vendor> <feature policy='require' name='tm2'/> <feature policy='require' name='est'/> <feature policy='require' name='monitor'/> <feature policy='require' name='ds'/> <feature policy='require' name='ss'/> <feature policy='require' name='vme'/> <feature policy='require' name='ht'/> <feature policy='require' name='dca'/> <feature policy='require' name='pbe'/> <feature policy='require' name='tm'/> <feature policy='require' name='vmx'/> <feature policy='require' name='ds_cpl'/> <feature policy='require' name='xtpr'/> <feature policy='require' name='acpi'/> <feature policy='disable' name='nx'/> <feature policy='disable' name='pae'/> </cpu> It wasn't working before I disabled PAE and NX. Double checked. If I delete <cpu> part and thus leave it 'default', the application won't work. Third, initially I couldn't use more than two cores with single instance of WinXP because every core was identified as a whole CPU and WinXP is limited to two CPU's. So the idea is to allocate 4 cores and specify topology as 2 cpu, 2 cores, 1 thead. But if I specify ANY cpu topology manually, WinXP uses 100% of all physical CPU cores assigned to them even if guest OS's load is zero. By the way, I got this behaviour from the very beginning if ACPI was turned off for guest OS (which was default). So I rolled back to NOT specifying CPU topology and allocating only two cores to WinXP. Bad... BUT it started working properly after I did the aforementioned 'optimisation' for tnat WinXP instance. Now I have it with 4 cores assigned. Mystery! Help me please, what did I do wrong way? Best regards, Dmitry Mikhailov Server configuration: 2x Intel(R) Xeon(R) CPU E5420 @ 2.50GHz 2x 2GB DDR-II FBDIMM Intel motherboard with 5000P Chipset Server's Mission: virtualization host system. Virtualized OS's: 1xFile server on CentOS 5.5/32bit 4xWinXP machines for rdesktop each. Software versions: Before: The kernel was 2.6.32-71.el6.x86_64 I'm sorry I don't have any data on software versions before upgrade. But it was stock CentOS 6.0. I didn't use CR. After: kernel-2.6.32-220.4.1.el6.x86_64 libvirt-0.9.4-23.el6_2.4.x86_64 qemu-kvm-0.12.1.2-2.209.el6_2.4.x86_64

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How many virtual guest 'cpus' can a core duo 'quad' core support
by James B. Byrne 23 Feb '12

23 Feb '12

CentOS-6.2 What is the maximum number of cpus can I configure for a single vm guest running on a host with this hardware? # lscpu Architecture: x86_64 CPU op-mode(s): 32-bit, 64-bit Byte Order: Little Endian CPU(s): 4 On-line CPU(s) list: 0-3 Thread(s) per core: 1 Core(s) per socket: 4 CPU socket(s): 1 NUMA node(s): 1 Vendor ID: GenuineIntel CPU family: 6 Model: 23 Stepping: 10 CPU MHz: 1998.000 BogoMIPS: 5331.76 Virtualization: VT-x L1d cache: 32K L1i cache: 32K L2 cache: 2048K NUMA node0 CPU(s): 0-3 I ask this because it occurs to me that I may have missed something fundamental respecting the use of the initialism CPU vice the term Cores. -- *** 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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virt February 2012