after online migration vm grows(ZFS/LVM)


New Member
May 15, 2019

I'm trying to test proxmox before migration from vmware.

Vmware: 8 old hosts, ~150 VM, all VM ~50 TB, 10 VM > 1TB, Incremental backup for 14 days to another DC. (increment for a day about 200GB)

Proxmox: 3 new hosts with a lot of RAM and SSD.

1) Is there any solution to make incremental backup VM with storage type raw, qcow2, lvm?(50 TB copy everyday it's too much)

2) After online(live) migration with storage type zfs VM grows from thin to full size, is there a way to prevent it?("discard" is on on FS inside VM, and in option storage VM)

3) After online(live) migration with storage type lvm VM grows from thin to full size, is there a way to prevent it?("discard" is on on FS inside VM, and in option storage VM)
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After growing VM i can do "dd if=/dev/zero of=file1; rm file1" and VM will be thin, but when VM > 4 TB it takes sooo long.
I would recommend once a week backup of VMs ,and because machines are very big just set up diff backups inside them(let's say like Oracle RMAN etc). So if something crashes you have vm backup and app backup.
For this 1 cluster and 150 VM i can do it, but i have 8 clusters more, about 25 hosts, more than 1000 VM.
I can't configure backup inside every VM. Right now i'm reading about zfs and pve-zsync.
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Hi Oleg,

Yes the size could increase in size using zfs as storage if you use pve-zsync if at source and at destination you will have different zfs storage (like zpool mirror-> raidz). Anyway pve-zsync is the best tool that you can use.

Also I would run before running pve-zsync a fstrim -a inside of the each VM.

Good luck!
I did some test with pve-zsync, and there is no problem with size of VM(always thin) , they not convert from thin to thick. It's good tool for backup.
But after online(live) migration, VM on local zfs convert from thin to thick(and "fstrim -av" doesn't help, but "dd if=/dev/zero of=file1; rm file1" work fine) .
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