Super slow Backup with pve 2.x

[RobFantini]

One trick I found for ZFS, to improve the FSYNC rate as reported by pveperf I did a:

zfs set zfs:zfs_nocacheflush = 1

Where /zfs was my zfs mount point. Obviously you would do that on the freenas server, my zfs was local on the proxmox machine.

Which zfs are you using? fuse or native linux?
as I do not see that setting on native linux . but may have missed it..

 

[Erk]

Which zfs are you using? fuse or native linux?
as I do not see that setting on native linux . but may have missed it..

Native linux as described in this blog

http://alexsluiter.com/blog/native-zfs-proxmox

 

[malakatronis]

Hi,

since i upgraded from PVE 1.9 to PVE 2.x i have on 2 of my 3 systems big problems with the backup-speed.
All 3 are in a cluster-configuration but only for simple administration. Every VM is on the local storage and so on.

I have experienced the same issue since the upgrade.

Do you get that sluggish backup speed for every CT?
Does the same happen if you get a backup of a fresh CT created from template?

In my case, it happened just for one CT. It turned out that the problem was due to having a large number (~3,000,000) of small (~1KB) files inside it.
Proxmox 1.9 runs the backup job for that CT without any problem, but Proxmox 2.1 does not if there are too many files inside.

PS: What's the file limit per VT in Proxmox 2.1? Where can I tune that value?

 

[cristianm]

Same issue here. Slow speed for KVM VPS backup via NFS into 2.1

 

[rengiared]

3 months later i have a solution (more or less)
last week freenas 8.3 was released and with this release the support of zfs v28
after installing the update and upgrading the zfs pool from v15 to v28 the backup speed was as good as with PVE1.9 und freenas8.2
so for me it seems like there is an issue with pve 2.x and zfs pools lower v28
for me its solved, maybe this info could be interesting for the people who reported the same problem in this thread
the speedup was with pve 2.1 and now 2.2, hopefully for ever cause i don't wont to do the backup without this performance again

 

[jerel]

I managed to solve my issues also... by changing the NFS to async. If I leave it on sync it will fail by 20Gb routinely. I've had it running for a number of weeks now on async with no issues.