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[libvirt-users] Create and revert to snapshot fails silently after device update on running domain
by Jasper Spit 18 Oct '12

18 Oct '12

Hi list, I'm having an issue with snapshot creation. Scenario: qemu 1.1 libvirt 0.9.12 I create a domain, and start it. The domain has 1 IDE cdrom device defined (see below). When started, I want to mount an ISO file to it. So I do updateDeviceFlags in libvirt-python or update-device in virsh (both have the same problem). This works fine, the ISO image becomes available to the domain. Now I create a snapshot on the still running domain using snapshotCreateXML in libvirt-python or snapshot-create in virsh. The command returns immediately without error (a normal snapshot takes several seconds to complete). If I revert to this snapshot this command also returns immediately without error, but the snapshot is not actually reverted to, the domain remains running in the same state as if nothing had happened (I test this by verifying console output and checking if a testfile is present on the domain). If I do not use the update device commands prior to creating a snapshot, all is well. If I remove the source from the cdrom device using update device, the snapshots work properly again. Any idea what causes this? Steps to reproduce using virsh: virsh # start 4d5d722b-864c-657e-0f39-55d1bafc760e Domain 4d5d722b-864c-657e-0f39-55d1bafc760e started virsh # snapshot-create 4d5d722b-864c-657e-0f39-55d1bafc760e Domain snapshot 1348653920 created virsh # snapshot-revert 4d5d722b-864c-657e-0f39-55d1bafc760e 1348653920 All is good, the snapshot is reverted to properly. Now I update the cdrom device: virsh # update-device 4d5d722b-864c-657e-0f39-55d1bafc760e deb.xml Device updated successfully virsh # snapshot-create 4d5d722b-864c-657e-0f39-55d1bafc760e Domain snapshot 1348654116 created Command returns instantly. virsh # snapshot-revert 4d5d722b-864c-657e-0f39-55d1bafc760e 1348654116 No errors, but the snapshot is not reverted to. Now I remove the <source .../> again and do an update-device. virsh # update-device 4d5d722b-864c-657e-0f39-55d1bafc760e deb-off.xml Device updated successfully virsh # snapshot-create 4d5d722b-864c-657e-0f39-55d1bafc760e Domain snapshot 1348654540 created virsh # snapshot-revert 4d5d722b-864c-657e-0f39-55d1bafc760e 1348654540 Snapshot is created and reverted to properly. virsh # dumpxml 4d5d722b-864c-657e-0f39-55d1bafc760e <domain type='kvm' id='135'> <name>4d5d722b-864c-657e-0f39-55d1bafc760e</name> <uuid>4d5d722b-864c-657e-0f39-55d1bafc760e</uuid> <memory unit='KiB'>786432</memory> <currentMemory unit='KiB'>786432</currentMemory> <vcpu placement='static'>1</vcpu> <os> <type arch='x86_64' machine='pc-1.1'>hvm</type> <boot dev='hd'/> <boot dev='cdrom'/> </os> <features> <acpi/> <apic/> <pae/> </features> <clock offset='utc'/> <on_poweroff>destroy</on_poweroff> <on_reboot>restart</on_reboot> <on_crash>destroy</on_crash> <devices> <emulator>/usr/bin/kvm</emulator> <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <source file='/data/images/debian-live-6.0.4-amd64-standard.iso'/> <target dev='hdc' bus='ide'/> <readonly/> <alias name='ide0-1-0'/> <address type='drive' controller='0' bus='1' target='0' unit='0'/> </disk> <disk type='file' device='disk'> <driver name='qemu' type='qcow2'/> <source file='/data/domains/2f8baacd-563c-b747-b621-c0ddb4aa84bd'/> <target dev='vda' bus='virtio'/> <alias name='virtio-disk0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/> </disk> <controller type='usb' index='0'> <alias name='usb0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/> </controller> <controller type='ide' index='0'> <alias name='ide0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/> </controller> <interface type='bridge'> <mac address='52:54:00:39:86:29'/> <source bridge='br0'/> <target dev='vnet2'/> <model type='virtio'/> <alias name='net0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/> </interface> <input type='tablet' bus='usb'> <alias name='input0'/> </input> <input type='mouse' bus='ps2'/> <graphics type='vnc' port='5902' autoport='yes'/> <video> <model type='vga' vram='9216' heads='1'/> <alias name='video0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/> </video> <memballoon model='virtio'> <alias name='balloon0'/> <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/> </memballoon> </devices> <seclabel type='none'/> </domain> deb.xml: <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <source file='/data/images/debian-live-6.0.4-amd64-standard.iso'/> <target dev='hdc' bus='ide'/> </disk> deb-off.xml: <disk type='file' device='cdrom'> <driver name='qemu' type='raw'/> <target dev='hdc' bus='ide'/> </disk> Thanks much, - Jasper

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[libvirt-users] R: Using libvirt to monitor virtual environment.
by robmail16＠libero.it 18 Oct '12

18 Oct '12

Hello I need a solution for monitoring and automatic migration of Guest vm machines. A good approach would be to determine which guests to migrate based on "trend usage algorithm". There is something in java and libvirt that could be used? RegardsRoberto ----Messaggio originale---- Da: vinicius.braga(a)lupa.inf.ufg.br Data: 18/10/2012 16.02 A: <libvirt-users(a)redhat.com> Ogg: [libvirt-users] Using libvirt to monitor virtual environment. Hey, I am new with libvirt. I am working to create a program to monitor a virtual environment. I have seen some solutions that use libvirt. Is this API good to make monitoring operations? I didn't see operations that show the CPU or memory usage, at least in Java binding. Are there operations like these, or we have to calculate based on lower level informations?

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[libvirt-users] 0.10.x incorrectly reporting currentMemory size
by Andrey Korolyov 18 Oct '12

18 Oct '12

Hi, <memory unit='KiB'>16777216</memory> <currentMemory unit='KiB'>1394380</currentMemory> <memtune> <hard_limit unit='KiB'>1594380</hard_limit> <soft_limit unit='KiB'>1494380</soft_limit> </memtune> results to: 0.10.x, .dominfo. or dumpxml | grep -i currentmemory Max memory: 16777216 KiB Used memory: 13977292 KiB 0.9.11-13: Max memory: 16777216 KiB Used memory: 1394380 KiB

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[libvirt-users] Migrating a LV backed guest
by Corey Quinn 18 Oct '12

18 Oct '12

I have a KVM VM that's backed by a logical volume on local disk. I'd like to copy / move it to an identically configured host. [root@virt2 cquinn]# virsh migrate --copy-storage-all --verbose --persistent node1.www qemu+ssh://10.102.1.11/system error: Unable to read from monitor: Connection reset by peer How should I effectively troubleshoot this? Am I misunderstanding how virsh migrate is supposed to work? Regards, Corey Quinn

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[libvirt-users] cgroup blkio.weight working, but not for KVM guests
by Ben Clay 17 Oct '12

17 Oct '12

I'm running libvirt 0.10.2 and qemu-kvm-1.2.0, both compiled from source, on CentOS 6. I've got a working blkio cgroup hierarchy which I'm attaching guests to using the following XML guest configs: VM1 (foreground): <cputune> <shares>2048</shares> </cputune> <blkiotune> <weight>1000</weight> </blkiotune> VM2 (background): <cputune> <shares>2</shares> </cputune> <blkiotune> <weight>100</weight> </blkiotune> I've tested write throughput on the host using cgexec and dd, demonstrating that libvirt has correctly set up the cgroups: cgexec -g blkio:libvirt/qemu/foreground time dd if=/dev/zero of=trash1.img oflag=direct bs=1M count=4096 & cgexec -g blkio:libvirt/qemu/background time dd if=/dev/zero of=trash2.img oflag=direct bs=1M count=4096 & Snap from iotop, showing an 8:1 ratio (should be 10:1, but 8:1 is acceptable): Total DISK READ: 0.00 B/s | Total DISK WRITE: 91.52 M/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND 9602 be/4 root 0.00 B/s 10.71 M/s 0.00 % 98.54 % dd if=/dev/zero of=trash2.img oflag=direct bs=1M count=4096 9601 be/4 root 0.00 B/s 80.81 M/s 0.00 % 97.76 % dd if=/dev/zero of=trash1.img oflag=direct bs=1M count=4096 Further, checking the task list inside each cgroup shows the guest's main PID, plus those of the virtio kernel threads. It's hard to tell if all the virtio kernel threads are listed, but all the ones I've hunted down appear to be there. However, when running the same dd commands inside the guests, I get roughly-equal performance - nowhere near the ~8:1 relative bandwidth enforcement I get from the host: (background ctrl-c'd right after foreground finishes, both started within 1s of each other) [ben@foreground ~]$ dd if=/dev/zero of=trash1.img oflag=direct bs=1M count=4096 4096+0 records in 4096+0 records out 4294967296 bytes (4.3 GB) copied, 104.645 s, 41.0 MB/s [ben@background ~]$ dd if=/dev/zero of=trash2.img oflag=direct bs=1M count=4096 ^C4052+0 records in 4052+0 records out 4248829952 bytes (4.2 GB) copied, 106.318 s, 40.0 MB/s I thought based on this statement: "Currently, the Block I/O subsystem does not work for buffered write operations. It is primarily targeted at direct I/O, although it works for buffered read operations." from this page: https://access.redhat.com/knowledge/docs/en-US/Red_Hat_Enterprise_Linux/6/ht ml/Resource_Management_Guide/ch-Subsystems_and_Tunable_Parameters.html that this problem might be due to host-side buffering, but I have that explicitly disabled in my guest configs: <devices> <emulator>/usr/bin/qemu-kvm</emulator> <disk type="file" device="disk"> <driver name="qemu" type="raw" cache="none"/> <source file="/path/to/disk.img"/> <target dev="vda" bus="virtio"/> <alias name="virtio-disk0"/> <address type="pci" domain="0x0000" bus="0x00" slot="0x04" function="0x0"/> </disk> Here is the qemu line from ps, showing that it's clearly being passed through from the guest XML config: root 5110 20.8 4.3 4491352 349312 ? Sl 11:58 0:38 /usr/bin/qemu-kvm -name background -S -M pc-1.2 -enable-kvm -m 2048 -smp 2,sockets=2,cores=1,threads=1 -uuid ea632741-c7be-36ab-bd69-da3cbe505b38 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/background.monitor,server,n owait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/path/to/disk.img,if=none,id=drive-virtio-disk0,format=raw,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virti o-disk0,bootindex=1 -netdev tap,fd=20,id=hostnet0,vhost=on,vhostfd=22 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:11:22:33:44:55,bus=pci.0,addr= 0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -device usb-tablet,id=input0 -vnc 127.0.0.1:1 -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 For fun I tried a few different cache options to try to force a bypass the host buffercache, including writethough and directsync, but the number of virtio kernel threads appeared to explode (especially for directsync) and the throughput dropped quite low: ~50% of "none" for writethrough and ~5% for directsync. With cache=none, when I generate write loads inside the VMs, I do see growth in the host's buffer cache. Further, if I use non-direct I/O inside the VMs, and inflate the balloon (forcing the guest's buffer cache to flush), I don't see a corresponding drop in background throughput. Is it possible that the cache="none" directive is not being respected? Since cgroups is working for host-side processes I think my blkio subsystem is correctly set up (using cfq, group_isolation=1 etc). Maybe I miscompiled qemu, without some needed direct I/O support? Has anyone seen this before? Ben Clay rbclay(a)ncsu.edu

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[libvirt-users] Migrating fails with "Timed out during operation: cannot acquire state change lock"
by Guido Winkelmann 17 Oct '12

17 Oct '12

Hi, After recently upgrading to 0.9.11 (as shipped with Fedora 17), I was just trying to migrate a qemu domain from one host to another (using virDomainMigrateToURI()), when I got this error message: Unsafe migration: Migration may lead to data corruption if disks use cache != none Okay, this is explainable (if a bit disappointing - I would have hoped that qemu would be able to disable disk caches before migration and then reenable them afterwards...). However, the next time I tried migrating the same domain, I got this error message after about 30 seconds: Timed out during operation: cannot acquire state change lock This looks like a bug to me - granted not a high profile one if it only happens when someone is retrying a failed migration, but still... Guido

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[libvirt-users] Connection using Java
by Felipe Oliveira Gutierrez 16 Oct '12

16 Oct '12

Hi, I am using java to connect to the xen, but my class is throwing a exception. Does anyone know what is happening? public class TestConnection { public static void main(String[] args) { Connect conn = null; try { conn = new Connect("xen+ssh://root@192.XXX.XXX.XX/", true); libvir: RPC error : End of file while reading data: nc: invalid option -- 'U' nc -h for help: Input/output error exception caught:org.libvirt.LibvirtException: End of file while reading data: nc: invalid option -- 'U' nc -h for help: Input/output error level:VIR_ERR_ERROR code:VIR_ERR_SYSTEM_ERROR domain:VIR_FROM_RPC hasConn:false hasDom:false hasNet:false message:End of file while reading data: nc: invalid option -- 'U' nc -h for help: Input/output error str1:%s str2:End of file while reading data: nc: invalid option -- 'U' nc -h for help: Input/output error str3:null int1:-1 int2:-1 Thanks, Felipe -- *-- Felipe Oliveira Gutierrez* *-- **lipe.82(a)gmail.com* <lipe.82(a)gmail.com> *-- https://sites.google.com/site/lipe82/Home/diaadia*

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[libvirt-users] LXC guest memory recycling under RHEL6
by Rudy Godoy Guillén 14 Oct '12

14 Oct '12

Hello, I'm running a LXC guest using libvirtd under RHEL6. The guest has this particular memory behavior that I'm unable to explain. I've the following memory settings for this guest's memory. Inside the guest I'm running a Apache webserver serving PHP scripts and static content. <memory unit='GB'>2</memory> <currentMemory unit='GB'>2</currentMemory> <memtune> <hard_limit unit='GB'>2</hard_limit> </memtune> Now, when querying using virsh dominfo I see the amount of used RAM increases every second and it gets to the point where it reaches the limit causing the guest to be unresponsive. The current solution is destroying the guest process (virsh destroy) and starting again, but the behavior repeats again. As I understand what is happening is that the amount of memory used by Apache's processes (4 mpm forks) is never released so every request causes more memory comsumption reaching that point. If I'm correct on this what can I do to handle it? thanks! -- Rudy Godoy http://stone-head.org

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[libvirt-users] What to configure for a guest with 2.2. kernel ...
by Stefan G. Weichinger 12 Oct '12

12 Oct '12

Greetings, libvirt-users ... I ask for help with virtualizing an ancient machine with a linux kernel 2.2. I already succeeded doing that but I face random performance issues and I somehow get lost in all the settings and options. I am using Virtual Machine Manager: * I can't chose something like Linux for the OS and 2.2 for the kernel. Does the combination "linux/2.4 kernel" work or should I choose "Other" or "Generic" ? * Later there I get a choice of "Architektur" (or "architecture" ? german here): for a 32bit-guest, should it be "i686" to reflect the environment for the guest or "x86_64" to fully use the potential of the host? Please forgive my questions, maybe they are FAQ somewhere, I really fiddled a lot already ... Thanks, Stefan

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[libvirt-users] Libvirt mpiexec networking issue
by Shawn Furrow 12 Oct '12

12 Oct '12

Hi all, Not sure if this is the best place to put this question since I'm not sure if it's a Libvirt issue but... I currently have two VMs up with networking and I can successfully ssh to and from each VM and I have confirmed that I can successfully download things from the internet. However, when trying to run mpiexec (which uses ssh), the connection fails and gives me the following errors: [proxy:0:0@guestVM] HYDU_sock_connect (./utils/sock/sock.c:188): unable to connect from "guestVM" to "guestVM" (Connection refused) [proxy:0:0@guestVM] main (./pm/pmiserv/pmip.c:205): unable to connect to server guestVM at port 56514 (check for firewalls!) Just so it is clear, I know that the two guests host names are the same (they are clones) but I am giving explicit IP address for the connection so it should not be an issue. Does any one know if there is something unique with how Libvirt networking is set up that would cause such an error? I have tried checking for firewalls and there don't seem to be any. Thanks, Shawn -- Virginia Tech Bradley Department of Electrical and Computer Engineering B.S. Electrical Engineering B.S. Computer Engineering

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