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[libvirt-users] /var/lib/libvirt/images on BTRFS (it works!)
by Gene Czarcinski 18 Nov '13

18 Nov '13

Some of you may be interested in running your qemu-kvm (or other) disk image files on BTRFS. After some fumbling around, I have found out how to do it so it works and works very well (especially if it is on an SSD). Anyone investigating running on BTRFS immediately finds out that there is a fragmentation problem (just putting image files on btrfs can result in them having between 50,000 and 100,000 extents). Some may have seen that adding nodatacow to the mount option is a solution ... it is not. So what is the solution? 1. execute: chattr +C /var/lib/libvirt/images or wherever your image files are. This needs to be done on the directory whether you have a separate subvol or not. 2. This ONLY works for new files and ONLY works for "raw" storage format files. Pretty much by definition, qcow2 files are sparse format files and that is the primary problem on btrfs. So that the vm creation wizard will create a new disk using the raw storage format, you need to select: Edit->Preferences->VM Details->Default Storage Format->Raw After then, an created virtual will have the correct disk format. You can use "filefrag" to verify that things are working. Gene

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[libvirt-users] How to tell libvirt not to use qemu "accel=kvm" for a FreeBSD guest
by Christian Gagneraud 15 Nov '13

15 Nov '13

Hi there, I have used qemu to install FreeBSD 9.2 release, and i can boot it fine with: $ qemu-system-x86_64 -hda images/FreeBSD-9.2-RELEASE-amd64.img I then made virsh aware of my brand new VM (see attached XML), but when i run it via virsh, It hangs after the bootloader whith this message: Booting... CPU doesn't support long mode From the log, here is the generated qemu command: LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/sbin:/sbin:/bin /usr/bin/qemu-system-x86_64 -name fbsd92-amd64 -S -machine pc-i440fx-1.5,accel=kvm,usb=off -m 512 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid 11ae165e-b8a2-5083-fb77-37c0042725bf -nographic -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/fbsd92-amd64.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 -drive file=/home/christiaga/projects/vms/images/FreeBSD-9.2-RELEASE-amd64.img,if=none,id=drive-ide0-0-0,format=raw -device ide-hd,bus=ide.0,unit=0,drive=drive-ide0-0-0,id=ide0-0-0,bootindex=1 -netdev tap,fd=24,id=hostnet0 -device rtl8139,netdev=hostnet0,id=net0,mac=52:54:00:9c:94:3b,bus=pci.0,addr=0x3 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x4 After many attempts, I pinned down the problem. To be able to boot the machine with the above command, I had to remove: * the accel=kvm in -machine * the -S (to "autostart" the VM) And change the -net tap,fd=24 to -net user,id=... So basically, the only thing i would like to tell libvirt is not to use accel=kvm, i guess the FreeBSD kernel is missing some feature (is it this PAE thing?) Does anyone how can i tell libvirt to do that? regards, Chris

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[libvirt-users] Problem about lxc-enter-namespace interface
by hzguanqiang＠corp.netease.com 14 Nov '13

14 Nov '13

Hi experts, When I test lxc-enter-namespace interface, it turned out such an error: hzguanqiang@debian:~$ vir version Compiled against library: libvirt 1.1.4 Using library: libvirt 1.1.4 Using API: LXC 1.1.4 Running hypervisor: LXC 3.9.6 hzguanqiang@debian:~$ vir list Id Name State ---------------------------------------------------- 1544 instance-00000015 running hzguanqiang@debian:~$ vir lxc-enter-namespace 1544 --noseclabel /bin/df -hl error: Cannot get namespaces for 1545: Function not implemented hzguanqiang@debian:~$ ls /proc/self/ns ipc mnt net pid user uts What's the problem? ------------------ Best regards! GuanQiang 2013-11-14

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[libvirt-users] UTS namespace
by Aarti Sawant 14 Nov '13

14 Nov '13

Hello, I am trying to set up UTS name space on centos 6.4 LXC container. one method is that we set the host name in /etc/sysconfig/network. hostname=test1 Is there any way so that i can set the hostname in libvirt xml while creating a container? I know using lxc-tools we can set hostname while creating by 2 ways - first while creating container using lxc-create -u test1 - Second by specifying lxc.utsname=test1 in config file Thanks Aarti Sawant NTTDATA OSS Center Pune

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[libvirt-users] User Namespace in LXC
by Saurabh Deochake 14 Nov '13

14 Nov '13

Hi all, I'm trying to restrict privileges of root user inside the container. I searched about it and got to know about "idmap" element in domain XML. I added "idmap" element in my container's XML file: <idmap> <uid start='0' target='1000' count='10'/> <gid start='0' target='1000' count='10'/> </idmap> I restarted the container with updated XML file. When I execute "id" command to know if root user inside the container has been mapped with an user from host, i still get output uid as 0 # id -u root 0 Am I doing the steps right to check the user namespacing? Please help me out with this. Thanks in advance, Saurabh Deochake. NTT DATA OSS Center, Pune, India

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[libvirt-users] Doc/web site problems
by Greg Ward 14 Nov '13

14 Nov '13

Hi all -- I have one meta-question, and two real questions. 1) What's the best place to report bugs in the docs, FAQ, web site, or wiki? I have found two -- see next points. (I'm happy to make the fixes myself if I can, but I'm pretty ignorant about libvirt. Can't fix the docs without knowing the truth.) 2) In the FAQ, under "networking is unavailable in virt-manager / virsh - libvirt's default network fails to start", it says "Here is a list of the networking-related packages that need to be installed for libvirt networking to work properly:". But it does not say if those packages are supposed to be installed on the host or the guest! It might be obvious to you, but it isn't to me. 3) In http://wiki.libvirt.org/page/Networking#Guest_configuration, it says "the following XML would be used in the guest:" ... but it doesn't say WHERE to put that configuration! Is it a snippet to add to an existing file? A new file I have to create? Something else? Very frustrating! ;-( Thanks -- Greg

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[libvirt-users] Migration function is not supported by the connection driver: virDomainMigrate2
by Joseph Perrin 14 Nov '13

14 Nov '13

Greetings; I'm running Fedora 19, Xen 4.2.3, libvirt 1.0.5.6. I have two identical servers x1 & x2. I've read http://libvirt.org/migration.html & I've created certificates for tls according to http://wiki.libvirt.org/page/TLSSetup I can do this on both servers, and from a third admin server: # virsh -c xen+tls://x1.localdomain hostname x1.localdomain and... # virsh -c xen+tls://x2.localdomain hostname x2.localdomain It appears I can connect without issues. No matter what I try, I cannot get migration to work :-( x 1000! I've created a test DomU named "z19", which uses a DRBD block device between the two hosts. It's running on x1, (and obviously not on x2), and I want to migrate it to x2. When I attempt to migrate I get the following. (Although, I've tried every permutation of syntax I've read about. The following appears to be most reasonable for my situation?) # virsh migrate --live z19 xen+tls://x2.localdomain error: this function is not supported by the connection driver: virDomainMigrate2 # virsh -c xen+tls://x1.localdomain migrate z19 xen+tls://x2.localdomain error: this function is not supported by the connection driver: virDomainMigrate2 # virsh migrate --live z19 xen+ssh://root@x2.localdomain error: this function is not supported by the connection driver: virDomainMigrate2 I've set libvirtd.conf: log_level=1 Which reports nothing. There is a great amount of conflicting information on this topic. It's difficult to ascertain which to listen to. Any suggestions you could give me would be greatly appreciated. -Joseph

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[libvirt-users] Lots of threads and increased IO load
by Gergely Horváth 14 Nov '13

14 Nov '13

Hello guys, We have a lot of small computers on top of two servers running QEMU/KVM virtualisation with libvirt. In this case, most of the VMs are not doing much work, some of them barely touches any "hardware" resources. I have two problems, they might be connected. When I do a bigger IO job on one of the VMs (like downloading files to local disk) all other VMs' IO load increases. Even our LDAP server's IO load is triggering an alert in our monitoring system - though that server barely does any IO throughout the day. The big IO job can NOT be considered big in the terms of the host computers IO capabilities, as it has two really fast SSD drives in hardware RAID 0 configuration. It can easily do hundreds of megabytes per second random write. The file copy I was running barely touched 50 MB/s. So this should not be a problem for the host's disks and I also do not understand why other computers IO load is increased. The second problem came when I looked at `iotop`, to see how much IO read and write is going on. The computer, that was doing the copying easily had like 20-30 threads writing pieces to the disk. Some of the threads are obviously "processor emulators" - they been running since the birth of the VM, but what are these other threads? TL;DR; Two questions than, to sum up everything: * How can I control and maybe decrease the number of threads spawned for a virtual machine? * How can I know what is the default IO caching for a VM, and what caching mechanism/policy should I set to minimise IO latency (i.e. I do not really care if the data is written to the disk later than the guest thinks) Thank you. P.S: We have been running hypertable servers the whole time, and even those did not generate such mess with IO... -- Üdvözlettel / Best regards Horváth Gergely | gergely.horvath(a)inepex.com IneTrack - Nyomkövetés egyszerűen | Inepex Kft. Ügyfélszolgálat: support(a)inetrack.hu | +36 30 825 7646 | support.inetrack.hu Web: www.inetrack.hu | nyomkovetes-blog.hu | facebook.com/inetrack Inepex - The White Label GPS fleet-tracking platform | www.inepex.com

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[libvirt-users] Problem with bridged network configuration
by Bob Doolittle 14 Nov '13

14 Nov '13

Hi, When I initially boot my system, it fails to bring up the network. Once booted, if I run "systemctl restart network.service", or even stop, wait a while, then start, it starts up fine and all is well. I'm running Fedora 19 (updated). I followed the instructions on this page to set up a bridged network: http://wiki.libvirt.org/page/Networking I note however that I did *not* have any bridge (for NAT use) configured initially by default on my system, and followed the directions on this page to create it: https://fedoraproject.org/wiki/Getting_started_with_virtualization I have disabled the NetworkManager service, and created network initscripts for my em1 and br0 interfaces. I notice from the systemctl status output, that the network failure is logged, and only *after* that the br0 interface comes up. So I wonder if there is some ordering problem in spite of the fact that I have specified DELAY=0 for br0. I have included output from the following commands: systemctl status network.service (initially, when failed to come up) brctl show ip link ip address Also attached are the network initscripts for my em1 and br0 interfaces. Any guidance would be much appreciated! Thanks, Bob

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[libvirt-users] Turning off polling
by Timothy Ehlers 13 Nov '13

13 Nov '13

Is it possible to turn off polling, we have 50~60 kvm instances per machine and have found that when libvirtd is running each KVM pid has 20% additional cpu usage. I turned on debug logging for 10 minutes and it seems to be 99% of this: virEventPollDispatchHandle But i cannot find a way to disable it. -- Tim Ehlers

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