June 2015 - Users - libvirt List Archives

[libvirt-users] bridge / ubuntu / no arp reply
by François Chenais 15 Oct '26

15 Oct '26

Hello I'm trying to setup a bridged guest on an ubuntu 13.10 but it doesn't work. (Everything is ok with NAT) Network sniffing shows that arp replies don't come back to the guest. Test 1 ------ Guest : ping host_bridge_ip (ok) Test 2 ------ Guest: ping other_lan_host (KO) other_lan_host - receives arp who-is request - sends arp reply - arp -a shows the guest macaddr => Guest doesn't receive reply Test 3 ------ other_lan_host ping the Guest (KO) - arp -a shows "incomplete" addr - Guest receives nothing On Host ------- network tcpdump on bridge or vnet interfaces shows request but no reply ... Thanks in advance for help or ideas François

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[libvirt-users] ceph rbd pool and libvirt manageability (virt-install)
by Jelle de Jong 28 Aug '18

28 Aug '18

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello everybody, I created a rbd pool and activated it, but I can't seem to create volumes in it with virsh or virt-install? # virsh pool-dumpxml myrbdpool <pool type='rbd'> <name>myrbdpool</name> <uuid>2d786f7a-2df3-4d79-ae60-1535bcf1c6b5</uuid> <capacity unit='bytes'>6997998301184</capacity> <allocation unit='bytes'>10309227031</allocation> <available unit='bytes'>6977204658176</available> <source> <host name='ceph01.powercraft.nl' port='6789'/> <host name='ceph02.powercraft.nl' port='6789'/> <host name='ceph03.powercraft.nl' port='6789'/> <name>libvirt-pool</name> <auth type='ceph' username='libvirt'> <secret uuid='029a334e-ed57-4293-bb99-ffafa8867122'/> </auth> </source> </pool> # virt-install --version 1.0.1 # virsh --version 1.2.9 I ended using virsh edit ceph-test.powercraft.nl and making creating the disk manually. <disk type='network' device='disk'> <auth username='libvirt'> <secret type='ceph' uuid='029a334e-ed57-4293-bb99-ffafa8867122'/> </auth> <source protocol='rbd' name='libvirt-pool/kvm01-storage'> <host name='ceph01.powercraft.nl' port='6789'/> <host name='ceph02.powercraft.nl' port='6789'/> <host name='ceph03.powercraft.nl' port='6789'/> </source> <target dev='vdc' bus='virtio'/> </disk> I use virt-install a lot to define, import and undefine domains, how can I use virt-install to manage my rdb disks? Kind regards, Jelle de Jong -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iJwEAQECAAYFAlV1xlQACgkQ1WclBW9j5HkbPQP+PjNrzvlqysslOp2Yk7wH4Mxy 2sh2dn96G0KOAHEeEn3BN6IWlnD1TADZbHdpTtMwkdv48Xwn0sP1s+3QDM4pb3gP n+z+dVxS8FouDIy/eiso3IBCj3g4TWbEX8ZHqs3jKqe0lZgAXBzB9xYSUowcEBrZ ddkPbr8p8ozWyOG+9V8= =lkK7 -----END PGP SIGNATURE-----

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[libvirt-users] virRandomBits - not very random
by Brian Rak 01 Jun '18

01 Jun '18

I just ran into an issue where I had about 30 guests get duplicate mac addresses assigned. These were scattered across 30 different machines. Some debugging revealed that: 1) All the host machines were restarted within a couple seconds of each other 2) All the host machines had fairly similar libvirtd pids (within ~100 PIDs of each other) 3) Libvirt seeds the RNG using 'time(NULL) ^ getpid()' This perfectly explains why I saw so many duplicate mac addresses. Why is the RNG seed such a predictable value? Surely there has to be a better source of a random seed then the timestamp and the pid? The PID seems to me to be a very bad source of any randomness. I just ran a test across 60 of our hosts. 43 of them shared their PID with at least one other machine.

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[libvirt-users] Libvirt bite sized tasks
by Michal Privoznik 20 Mar '16

20 Mar '16

Dear lists, I've just started new wiki page which aim is to summarize small and trivial tasks, that starting contributors can take, investigate and implement. The aim is to give them something easy to start with while not scaring them out about complexity of our code. The page can be found here: http://wiki.libvirt.org/page/BiteSizedTasks The name is copied from qemu wiki: http://wiki.qemu.org/BiteSizedTasks Please, feel free to extend the list. I plan to use it in the future when interviewing GSoC candidates. Michal

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[libvirt-users] virDomainCoreDumpWithFormat files created as root
by NoxDaFox 18 Nov '15

18 Nov '15

Greetings, I am dumping a guest VM memory for inspection using the command "virDomainCoreDumpWithFormat" and the created files appear to belong to root (both user and group). I have searched around but didn't find any answer. Is there a way to instruct QEMU to create those files under a different user? Thank you.

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[libvirt-users] Access to virtualization on a multi-user system
by sbaugh＠catern.com 08 Jul '15

08 Jul '15

Hi libvirt-users, I find myself wanting to do something that seems like it must have some obvious solution: I have multiple users (let's just assume local Unix accounts) on a Linux system, and I want them all to have access to KVM-accelerated virtualization. But, I don't want them to be able to meddle with each other's virtual machines. Is there a solution to this problem? Methods of attack that have occured to me: - Use PolicyKit to only allow a user to access qemu:///system VMs that are somehow marked as owned by that user - Run multiple libvirt qemu:///system daemons and restrict access to each on a per-user basis - Allow qemu:///session VMs to actually be KVM-accelerated (this seems like the best way to do it, but I have no idea if that's even possible) Again, the third seems like the best way, but I'm not sure of how to allow such VMs to be KVM-accelerated, and not sure if it's possible for them to use anything other than usermode networking. Hopefully I'm missing some obvious way to do it! Thanks for any assistance!

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[libvirt-users] Slow network performance issues
by Alex Regan 03 Jul '15

03 Jul '15

Hi, I have a fedora21 system that's been running fine under normal network activity, but trying to perform a full backup of the 300GB filesystem is taking forever because the network speed appears to be very slow. Using rsync, the transfer speeds reach a max of like 180kB/s. Using rsync to copy files on the local filesystem is greater than 55MB/s, so I don't think it's a disk issue. What kind of network speed can I expect copying data across the network from the guest to another host on the same gigabit network? I'm using the virtio driver: # lsmod|grep virtio virtio_console 28672 0 virtio_balloon 16384 0 virtio_net 32768 0 virtio_blk 20480 4 virtio_pci 24576 0 virtio_ring 20480 5 virtio_blk,virtio_net,virtio_pci,virtio_balloon,virtio_console virtio 16384 5 virtio_blk,virtio_net,virtio_pci,virtio_balloon,virtio_console ethtool on the vnet0 interface shows the speed at only 10Mb/s. Is that normal? Or even changable? I've included the qemu command-line below. # ps ax|grep propguest 1582 ? Sl 25433:37 /usr/bin/qemu-system-x86_64 -machine accel=kvm -name propguest -S -machine pc-1.2,accel=kvm,usb=off -m 16384 -realtime mlock=off -smp 4,sockets=4,cores=1,threads=1 -uuid b67e10fe-7ef0-a1ca-cecf-3f3506d54e1a -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/propguest.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -device virtio-serial-pci,id=virtio-serial0,bus=pci.0,addr=0x5 -drive file=/var/lib/libvirt/iso-images/Fedora-18-x86_64-DVD.iso,if=none,id=drive-ide0-1-0,readonly=on,format=raw -device ide-cd,bus=ide.1,unit=0,drive=drive-ide0-1-0,id=ide0-1-0 -drive file=/var/lib/libvirt/images/propguest.img,if=none,id=drive-virtio-disk0,format=qcow2 -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -drive file=/var/lib/libvirt/images/propguest-2.img,if=none,id=drive-virtio-disk2,format=raw -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x9,drive=drive-virtio-disk2,id=virtio-disk2 -netdev tap,fd=23,id=hostnet0,vhost=on,vhostfd=24 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:11:66:5a:51,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -chardev spicevmc,id=charchannel0,name=vdagent -device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0 -device usb-tablet,id=input0 -spice port=5900,addr=127.0.0.1,disable-ticketing,seamless-migration=on -device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,bus=pci.0,addr=0x2 -device intel-hda,id=sound0,bus=pci.0,addr=0x4 -device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x8 Any ideas greatly appreciated. Thanks, Alex

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[libvirt-users] qemu-img snapshots configuration
by sergio 30 Jun '15

30 Jun '15

Hello. What it the difference in external snapshot configuration with and without <domainsnapshot> ? What is the difference between vda and vdb in the following example? (From https://libvirt.org/formatsnapshot.html) <domainsnapshot> ... <memory snapshot='no'/> <disks> <disk name='vda' snapshot='external'> <driver type='qcow2'/> <source file='/path/vda-delta.qcow2'/> </disk> <disk name='vdb' snapshot='no'/> </disks> <domain> ... <devices> <disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/path/vda-img.qcow2'/> <target dev='vda' bus='virtio'/> </disk> <disk type='file' device='disk' snapshot='external'> <driver name='qemu' type='raw'/> <source file='/path/vdb-img.qcow2'/> <backingStore type='file'> <format type='qcow2'/> <source file='/path/vdb-delta.qcow2'/> </backingStore> <target dev='vdb' bus='virtio'/> </disk> ... </devices> </domain> </domainsnapshot> -- sergio.

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[libvirt-users] QEMU-KVM and bare metal performance impact
by nishtala 30 Jun '15

30 Jun '15

Hi, My name is Rajiv Nishtala and I am a PhD student in UPC. I am trying to investigate the performance (instructions per second (IPS)) impact of an application on QEMU-KVM and bare metal using the performance monitoring tools perfmon and perf. The performance counter used for measuring this is "instructions" and "instructions_retired" on perf and perfmon, respectively. The application is a *stress* microbenchmark that does not produce any cache misses (LLC). I account for the performance of the application on QEMU-KVM using the following procedure: A) Record the IPS of the QEMU-KVM (using its PID) on perf and perfmon when idle. B) Launch the stress benchmark and record IPS. C) the difference between *B* and *A* should give the performance of the application since the KVM does not inherently provide a technique to collect this statistic. However the performance of the application on bare metal is recorded as is using the per-thread session available in perfmon and perf. The sampling frequency to collect the statistics is 1 second. The result obtained on bare metal are in the order of magnitude of billions. On the other hand, results from KVM do not show any difference in performance when idle or when an application is running and is in the order of magnitude of 100's of thousands. IPS_KVM_IDLE LLC_KVM_IDLE IPS_KVM_STRESS LLC_KVM_STRESS IPS_bare metal_STRESS LLC_bare metal_STRESS 47902 2495 25157 600 8116556011 3805 23437 758 48762 1032 8166564000 2140 834370 9954 543690 2379 8326333629 234 25261 662 49139 997 8057453733 1399 47998 2767 23773 600 8214761042 494 542039 2299 843266 2231 8075529487 4593 47982 2781 25249 603 8327678364 443 23833 794 49138 622 8058893864 1870 832913 9978 544567 2204 8210889659 394 I also tried using perf-kvm using the following command: sudo perf kvm --guest --guestkallsyms=guest-kallsyms --guestmodules=guest-modules record -a -o perf.data but failed with the following error: *Couldn't record guest kernel [0]'s reference relocation symbol. *and no events were recorded. I describe details of QEMU and the host machine (bare metal) below. QEMU emulator version 2.0.0 in conjunction with KVM as the virtual environment and libvirt 1.2.2 The guest machine is running kernel version 3.19.0-15-generic and the host machine is running version 3.14.5-031405-generic on a x86_64 machine I setup the guest machine with Intel SandyBridge processor (model name:Intel Xeon E312xx) with the following flags: sockets=2,cores=2,threads=1 and 4mb cache. More details: cpu family : 6 model : 42 max freq : 2394.560 MHz flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ss ht syscall nx rdtscp lm constant_tsc rep_good nopl eagerfpu pni pclmulqdq vmx ssse3 cx16 pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx hypervisor lahf_lm vnmi ept xsaveopt The host machine is an Intel Sandy Bridge processor (Intel(R) Core(TM) i7-2760QM CPU @ 2.40GHz) with 4 cores and 6mb cache. cpu family : 6 model : 42 flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm ida arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid Thanks Rajiv Nishtala WARNING / LEGAL TEXT: This message is intended only for the use of the individual or entity to which it is addressed and may contain information which is privileged, confidential, proprietary, or exempt from disclosure under applicable law. If you are not the intended recipient or the person responsible for delivering the message to the intended recipient, you are strictly prohibited from disclosing, distributing, copying, or in any way using this message. If you have received this communication in error, please notify the sender and destroy and delete any copies you may have received. http://www.bsc.es/disclaimer

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[libvirt-users] qemu-img snapshots configuration
by sergio 30 Jun '15

30 Jun '15

Hello. What it the difference in external snapshot configuration with and without <domainsnapshot> ? What is the difference between vda, vdb and vdc in the following example? (From https://libvirt.org/formatsnapshot.html) <domainsnapshot> ... <memory snapshot='no'/> <disks> <disk name='vda' snapshot='external'> <driver type='qcow2'/> <source file='/path/vda-delta.qcow2'/> </disk> <disk name='vdb' snapshot='no'/> <disk name='vdc' snapshot='no'/> </disks> <domain> ... <devices> <disk type='file' device='disk'> <driver name='qemu' type='raw'/> <source file='/path/vda-img.qcow2'/> <target dev='vda' bus='virtio'/> </disk> <disk type='file' device='disk' snapshot='external'> <driver name='qemu' type='raw'/> <source file='/path/vdb-img.qcow2'/> <target dev='vdb' bus='virtio'/> </disk> <disk type='file' device='disk' snapshot='external'> <driver name='qemu' type='raw'/> <source file='/path/vdc-img.qcow2'/> <backingStore type='file'> <format type='qcow2'/> <source file='/path/vdc-delta.qcow2'/> </backingStore> <target dev='vdc' bus='virtio'/> </disk> ... </devices> </domain> </domainsnapshot> -- sergio.

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