Having downtimes on KVM LVM snapshoots

[jmjosebest]

Hi all, I'm having problems during backup process because I can not get a zero-downtime backup process.

In my Proxmox server I have installed a new disk, SSD, with a VolumeGroup, and added to Proxmox storages.
I create a VM KVM using around 80% of the disk space available, VirtIO driver + RAW + direct LVM.

The backup server is a NFS storage.

The nodes and the NFS server are connected in a private network in the same rack

Checking with "lvs" all the process is Ok with many space available on the VG.

But on every backup I get around 1-5 minutes of downtime.
SSH connections to the KVM machine is unavailable...
Log shows that the live backup was Ok, but no...

INFO: Starting Backup of VM 104 (qemu)
INFO: status = running
INFO: exclude disk 'virtio1' (backup=no)
INFO: exclude disk 'virtio2' (backup=no)
INFO: backup mode: snapshot
INFO: ionice priority: 7
INFO:   Logical volume "vzsnap-pveabs3-0" created
INFO: creating archive '/mnt/pve/nfsabs1-private/dump/vzdump-qemu-104-2013_01_02-00_00_01.tar.lzo'
INFO: adding '/mnt/pve/nfsabs1-private/dump/vzdump-qemu-104-2013_01_02-00_00_01.tmp/qemu-server.conf' to archive ('qemu-server.conf')
INFO: adding '/dev/ssd3/vzsnap-pveabs3-0' to archive ('vm-disk-virtio0.raw')
INFO: Total bytes written: 450971569152 (108.09 MiB/s)
INFO: archive file size: 26.31GB
INFO: delete old backup '/mnt/pve/nfsabs1-private/dump/vzdump-qemu-104-2012_12_30-12_00_01.tar.lzo'
INFO: Finished Backup of VM 104 (01:07:02)
INFO: Backup job finished successfully
TASK OK

 

[dietmar]

But on every backup I get around 1-5 minutes of downtime.

Maybe there is just too much load on the network? Try to set a bwlimit in /etc/vzdump.conf (see 'man vzdump')

 

[jmjosebest]

Seems is the solution

INFO: Starting Backup of VM 152 (qemu)
INFO: status = running
INFO: exclude disk 'virtio1' (backup=no)
INFO: backup mode: snapshot
INFO: bandwidth limit: 51200 KB/s
INFO: ionice priority: 7
INFO:   Logical volume "vzsnap-pveabs2-0" created
INFO: creating archive '/mnt/pve/nfsabs1-private/dump/vzdump-qemu-152-2013_01_04-12_19_54.tar.lzo'
INFO: adding '/sata1/tmpovz2/vzdumptmp872857/qemu-server.conf' to archive ('qemu-server.conf')
INFO: adding '/dev/ssd2/vzsnap-pveabs2-0' to archive ('vm-disk-virtio0.raw')
INFO: Total bytes written: 450971569152 (49.99 MiB/s)
INFO: archive file size: 162.02GB
INFO: delete old backup '/mnt/pve/nfsabs1-private/dump/vzdump-qemu-152-2013_01_01-12_20_26.tar.lzo'
INFO: Finished Backup of VM 152 (02:23:31)
INFO: Starting Backup of VM 153 (qemu)
INFO: status = running
INFO: exclude disk 'virtio1' (backup=no)
INFO: exclude disk 'virtio2' (backup=no)
INFO: backup mode: snapshot
INFO: bandwidth limit: 51200 KB/s
INFO: ionice priority: 7
INFO:   Logical volume "vzsnap-pveabs2-0" created
INFO: creating archive '/mnt/pve/nfsabs1-private/dump/vzdump-qemu-153-2013_01_04-14_43_25.tar.lzo'
INFO: adding '/sata1/tmpovz2/vzdumptmp872857/qemu-server.conf' to archive ('qemu-server.conf')
INFO: adding '/dev/ssd3/vzsnap-pveabs2-0' to archive ('vm-disk-virtio0.raw')
INFO: Total bytes written: 461708986880 (49.99 MiB/s)
INFO: archive file size: 175.42GB
INFO: delete old backup '/mnt/pve/nfsabs1-private/dump/vzdump-qemu-153-2013_01_01-14_37_49.tar.lzo'
INFO: Finished Backup of VM 153 (02:27:01)
INFO: Backup job finished successfully
TASK OK