What has the greatest impact on OpenVZ VPS suspend time during vzdump?

[ICPH]

Hi,

on an OpenVZ server there is tool vzdump to backup VMs

one can backup large VPS and it will be down maybe even seconds. It is true, but only in some cases..

I use 

vzdump 777 --mode suspend

About vzdump modes:

"stop" mode


Stop the VM during backup. This results in a very long downtime.

"suspend" mode
For OpenVZ, this mode uses rsync to copy the VM to a temporary location (see option --tmpdir). Then the VM is suspended and a second rsync
copies changed files. After that, the VM is started (resume) again. This results in a minimal downtime, but needs additional space to hold the
VM copy.

For QemuServer, this mode work like "stop" mode, but uses suspend/resume instead of stop/start.

"snapshot" mode
This mode uses LVM2 snapshots. There is no downtime, but snapshot mode needs LVM2 and some free space on the corresponding volume group to
create the LVM snapshot.

i want to ask how to prevent big downtime during vzdump backup.

my downtime was 15 minutes when i backed up around 80Gb VM on 7200RPM HDD

What has the biggest impact on downtime period? some directory on a VM, so i can reduce its size?

As per description above, what about somehow doing not more rsnyc before suspension? I also remember that when i suspended manually some big VM it toook very long time to be done..

 

[KuJoe]

Do an online backup with vzdump, no downtime at all.

 

[MartinD]

Doing a dump to the same single hdd the vm is stored on won't be helping either.

 

[rmlhhd]

Do an online backup with vzdump, no downtime at all.

Exactly this...

 

[ICPH]

thx, for advice, please can You kindly write an example on what you mean by "online backup with vzdump"?

If you mean "snapshot: Use LVM2 (no downtime, online)", 

How i can discover setup LVM if server has Raid 1 only?

Filesystem            Size  Used Avail Use% Mounted on

/dev/md2              2.0T  150G  1.8T   8% /

tmpfs                 7.7G     0  7.7G   0% /dev/shm

/dev/md1              496M   30M  441M   7% /boot

 

[Geek]

See example #1 - https://openvz.org/Backup_of_a_running_container_with_vzdump