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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 24 Feb '12

24 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 22 Feb '12

22 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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Re: [CentOS-virt] Unable to use all the memory available
by James B. Byrne 22 Feb '12

22 Feb '12

On Tue, February 21, 2012 02:23, Henry Addington wrote: > Hello: > > As you can see from xm info below, we have almost 200GB of > memory in our > server running CentOS 5.2. But, we can't seem to allocate > all the memory. > For some reason, the total memory that can be allocated > maxes out at 188.4 > GB. None of the VMs has hit its own max-mem limit. Even > when we set one of > the VM's memory so the total is above 188.4 GB, its memory > allocation stops > when the total memory allocation reaches 188.4 GB. > > Thanks for your assistance. > What is the hardware limit for the server? -- *** 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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Unable to use all the memory available
by Henry Addington 21 Feb '12

21 Feb '12

Hello: As you can see from xm info below, we have almost 200GB of memory in our server running CentOS 5.2. But, we can't seem to allocate all the memory. For some reason, the total memory that can be allocated maxes out at 188.4 GB. None of the VMs has hit its own max-mem limit. Even when we set one of the VM's memory so the total is above 188.4 GB, its memory allocation stops when the total memory allocation reaches 188.4 GB. Thanks for your assistance. HS release : 2.6.18-274.7.1.el5xen version : #1 SMP Thu Oct 20 17:06:34 EDT 2011 machine : x86_64 nr_cpus : 32 nr_nodes : 1 sockets_per_node : 8 cores_per_socket : 4 threads_per_core : 1 cpu_mhz : 2293 hw_caps : 178bfbff:efd3fbff:00000000:00000110:00802009:00000000:000007ff total_memory : 196607 free_memory : 0 node_to_cpu : node0:0-31 xen_major : 3 xen_minor : 1 xen_extra : .2-274.7.1.el5 xen_caps : xen-3.0-x86_64 xen-3.0-x86_32p hvm-3.0-x86_32 hvm-3.0-x86_32p hvm-3.0-x86_64 xen_pagesize : 4096 platform_params : virt_start=0xffff800000000000 xen_changeset : unavailable cc_compiler : gcc version 4.1.2 20080704 (Red Hat 4.1.2-51) cc_compile_by : mockbuild cc_compile_domain : centos.org cc_compile_date : Thu Oct 20 16:13:16 EDT 2011 xend_config_format : 2

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CentOS 6.2: Start and use guest as regular user under qemu-kvm?
by David McGuffey 11 Feb '12

11 Feb '12

Trying to set up a copy of CentOS 6.2 for home use and give each family member their own guest. Goal is to cripple the host so that no meaningful work can be done through it and each family member must use their own guest. "Gold Disk" masters would be kept of each guest, so if they screw it up, I can simply overwrite their current guest from the master. SELinux is enabled and sVirt separates each guest (I want to keep it that way). Default settings require a regular user to run the Virtual Machine Manager via sudo. Once they do that, they can see (and access) any other family member's guest. Would really like to avoid this. Have read several blurbs about getting qemu-kvm to run under a regular user, but not sure if the version provided with CentOS 6 is compiled with the options to allow that. When I follow the guidance to put users in the kvm group and change the ownership of key files, I fail. Appears to me that qemu-kvm with CentOS 6 is not set up (compliled) to run under a regular user. Say users are u1, u2, u3, and u4, and all are in the kvm group. What else do I need to do to allow them to start, suspend, and stop their own guest VM? Dave

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virt-io drivers for 64 bit Win7 needed for USB passthrough?
by David McGuffey 11 Feb '12

11 Feb '12

Have been trying to get a 64-bit Win7 guest to access a usb thumbdrive (and eventually an Apple iTouch). Host is CentOS 6.2 and the guest is running under qemu-kvm with SELinux enabled and sVirt separating guests from each other and guests from the host. Do I need to install the virt-io drivers in the Win7 guest, or are there more permission and SELinux blocks in my path? Dave

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Re: [CentOS-virt] Setting up serial ports on kvm guests
by James B. Byrne 08 Feb '12

08 Feb '12

On Wed, February 8, 2012 11:06, Ed Heron wrote: > On Tue, 2012-01-31 at 14:01 -0500, James B. Byrne wrote: >> CentOS-6.2 >> >> We have a dedicated CentOS-5.7 host used for fax >> reception >> and transmission that we wish to move to a CentOS-6.2 >> virtual guest instance. The CentOS-6.2 virtual host has >> a >> 4-port serial card installed. > > Consider replacing your multi-serial port card with a > VoIP analog > gateway and use a pre-rolled Asterisk with virtual > faxmodems, like > Elastix. Just make sure your codec is high enough > quality. We used to > receive faxes using a dedicated Linux box with a Comtrol > Rocketport and > an USRobotics MP8. We Converted to SIP trunks and managed > to get our > faxes in the SIP trunks, as well. > > This will remove the PCI pass-through from the equation. > After a brief read this seems to me the approach we should take. Recently I have discovered more about irqs, timing delays, and the difficulties/impossiblities of switching hardware from vm instances than I ever wanted to know. Given that we have three dedicated fax lines and 6 voice is there any hardware that would you suggest for a 4 core x86_64 Intel based host system? We have looked at going completely to v/f-oip but I do not have the time to deal with those intricacies and get this move completed at the same time. So, for the nonce it appears that we would have to employ an FXO gateway to connect our existing POTS lines to the host. -- *** 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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