[libvirt-users] backup KVM qcow2 over btrfs or zfs
by Francesco Morosinotto
Hi everybody,
I'm trying to implement in the non profit organization where I work a
backup strategy for our VMs.
At the moment I weekly backup the machine (on sunday nights) by stopping
the vm, making a snapshot, exporting the xml descriptor file and syncing
these files to a remote backup server.
I would really like to make daily snapshot without shutting down the vms.
at the moment the vms qcow2 disks are stored over an ext4 partition but
I'm planning to move them over a das with a new generation filesystem.
I'm trying out zfs and btrfs looking for the best one (at the moment zfs
seems to be more stable and somehow easy, flexible, while btrfs seems to
have better performance on my linux box).
I'm choosing one of these two FS in order to use theire instant-snapshot
feature;
my project will be to pause the vm, dump the memory and the xml
descriptor file, make a snapshot of the subvolume storing the qcow2 file
and the resuming the machine back (in I hope less than 10 seconds of
downtime).
what do you guys suggest me?
Am I going to experience bad performance having qcow2 over btrfs?
I was reading something like that but the posts were really backdated...
any hints is really appreciated
Thank you
Francesco
10 years
[libvirt-users] Any recommendation about benchmarking tools on Linux virtual machine?
by Allen Qiu
Hi all,
Do you have any recommendation about benchmarking tools on Linux virtual machine for measure the potential performance hit by virtualization, especially on multi-threads computation, since I doubt if the CentOS VM can fully make use of the 32 vCPUs (out of 64 physical cores) that I allocated to it.
Regards,
Allen
2014-11-05
Allen Qiu
10 years
[libvirt-users] setvcpus libvirt 1.2.9
by Thomas Stein
Hello.
I'm struggeling a little bit with the setvcpus command. I'm trying now
to get this running for a linux VM. Here is what i have:
<vcpu placement='auto' current='2'>4</vcpu>
Now the VM is starting with 2 CPUs. When i try to increase the number of
CPUs i get:
setvcpus dev --guest 4
error: invalid argument: requested vcpu count is greater than the count
of enabled vcpus in the domain: 4 > 2
Strange thing is when i set in the xml file:
<vcpu placement='auto' current='4'>4</vcpu>
the VM starts with 4CPUs and setting the CPUs works.
I can do:
setvcpus dev --guest 2
and:
setvcpus dev --guest 4
Is this a bug? Should i try to upgrade to 1.2.10? There seem to be a lot
of changes in it regarding setvcpus.
thanks and cheers
t.
10 years
[libvirt-users] setvcpus --guest on windows
by Thomas Stein
Hello.
Just a quick question. Is "setvcpus $windowsVM --guest 4" supposed to
work? I have qemu-guest-agent (1.6.something) running inside a windows7
vm but all i get is:
virsh # setvcpus windows7 --guest 4
error: invalid argument: requested vcpu count is greater than the count
of enabled vcpus in the domain: 4 > 1
The xml file looks like this:
<vcpu placement='static' current='1'>4</vcpu>
cheers
t.
10 years
[libvirt-users] old vm cannot be migrated, new vm can be migrated
by gustavo panizzo (gfa)
scenario:
i run a mix of libvirt 1.1.1 and 1.2.2 on the source hosts, 1.2.2 on the
destination hosts
qemu: 1.5.0+dfsg-3ubuntu5.3~cloud0 on all the hosts
openstack havana and icehouse
description:
i have many compute nodes running libvirt+kvm, when i try to migrate
guest that were created months ago it fails, if i create a vm and then
migrate it works
the problem is that libvirt cannot retrieve the mtu of the bridge were
the interfaces are be attached, but bridge is there (up and running)
$ grep qbr32740ab3-b6 /var/log/libvirt/libvirtd.log
2014-11-05 08:44:53.013+0000: 35311: debug : udevGetDeviceProperty:121 :
udev reports device 'qbr32740ab3-b6' does not have property 'DRIVER'
2014-11-05 08:44:53.013+0000: 35311: debug : udevGetDeviceType:1217 :
Could not determine device type for device with sysfs name 'qbr32740ab3-b6'
2014-11-05 08:44:53.013+0000: 35311: debug : udevAddOneDevice:1392 :
Discarding device -1 0x7f36e80bd5c0 /sys/devices/virtual/net/qbr32740ab3-b6
2014-11-05 08:44:53.013+0000: 35311: debug :
udevProcessDeviceListEntry:1414 : Failed to create node device for udev
device '/sys/devices/virtual/net/qbr32740ab3-b6'
2014-11-05 08:45:08.458+0000: 35303: error :
virNetClientProgramDispatchError:175 : Cannot get interface MTU on
'qbr32740ab3-b6': No such device
# ip l show dev qbr32740ab3-b6
639: qbr32740ab3-b6: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc
noqueue state UP
link/ether 72:d5:db:f6:b5:30 brd ff:ff:ff:ff:ff:ff
# brctl show qbr32740ab3-b6
bridge name bridge id STP enabled interfaces
qbr32740ab3-b6 8000.72d5dbf6b530 no qvb32740ab3-b6
tap32740ab3-b6
the difference between a new defined domain and an old one
is this
< <alias name='pci0'/>
---
> <alias name='pci.0'/>
> <timer name='hpet' present='no'/> ---> old domain does not have it
i even tried patching src/util/virnetdev.c to remove the check and
always return 1500 but the same thing happens
i'm lost i don't know where to look at it, any clue were to look is
appreciated
--
1AE0 322E B8F7 4717 BDEA BF1D 44BB 1BA7 9F6C 6333
10 years
[libvirt-users] ioremap error during bootup
by Allen Qiu
Hi all,
Does anybody have an idea about this "ioremap error" during the booting stage of VM CentOS7, although it can eventually bootup successfully.
Regards,
Allen
2014-11-05
Allen Qiu
10 years
[libvirt-users] fstrim support in libvirt/qemu guests
by Dennis Jacobfeuerborn
Hi,
I'm trying to find out how to enable fstrim support for libvirt/qemu
guests. Specifically I'm trying to enable this on a CentOS 7 host (qemu
1.5). I searched the web but only found very vague information and no
clear documentation on the requirements or how to modify the guest xml
to enable discard/fstrim support.
Can someone point me in the right direction?
Regards,
Dennis
10 years
[libvirt-users] The USB passthrough that refuses to die
by Mauricio Tavares
In trying to find out why my usb passthrough is not working, I decided
to edit (virsh edit) the config file for the vm client, removing the
following lines
<hostdev mode='subsystem' type='usb' managed='yes'>
<source>
<vendor id='0x051d'/>
<product id='0x0002'/>
</source>
</hostdev>
checking with "virsh dumpxml" that the lines went away, and then restarting
[root@vmhost ~]# virsh start nagios
error: Failed to start domain nagios
error: internal error Did not find USB device 51d:2 bus:2 device:3
[root@vmhost ~]#
As you can see, it is still acting like the usb device is defined.
What am I missing here?
10 years
[libvirt-users] KVM incremental backup using CBT
by Jd
Hi
Looking in to implementing (CBT like) delta backup for KVM.
The following looks promising..(last paragraph)
http://wiki.qemu.org/Features/Snapshots2
* In the last para, there is a mention of copy the blocks from the
disk using dirty-bitmap as reference. How to accomplish this ?
block-mirror with bitmap or is there a qemu-img command ? some details
would be appreciated.
// backup software now reads foo.img using t0_dirty.dbmp to perform incremental backup, when finished
* The backup after few runs in the backup store would be base
image + bunch of delta blocks ? Will this be same as base disk and bunch
of deltas ? or there is some special way to merge these ?
* I am assuming this scheme (snapshot, bitmap, block merge etc.)
should work with base disk in raw (non-qcow) format as well ? Right ?
i.e. will it work when the storage disk is iscsi, lvm, fc ? std linux
block device?
* Are there libvirt-api/verbs for doing some of this or we will
have to sue the qemu-monitor-command ?
* What version of qemu/kvm will have the core capabilities and
which min libvirt version would be sufficient ?
Is there a better way to do incremental backup / CBT like backup
than one mentioned here ?
Thanks
/Jd
10 years
[libvirt-users] quick question on schedinfo
by Yasser Shalabi
Hey everyone,
Can anyone explain the scedinfo parameters? I am wondering if I can use
this, (along with host side niceness scheduler tweaks) to cause vCPUs to
dominate the total time of the CPUs they are pinned to.
Here are the sched info parameters:
Scheduler : posix
cpu_shares : 0
vcpu_period : 0
vcpu_quota : 0
emulator_period: 0
emulator_quota : 0
The documentation (
http://libvirt.org/sources/virshcmdref/html/sect-schedinfo.html) is not yet
filled for this.
If anyone can explain these parameters, or point me to relevant code it
would be helpful!
Thanks
Yasser
10 years
