[SOLVED] limit scrubbing utilization?

[itwkpbs]

Hi there,

We have a ZFS raidz2 with 6x Seagate Exos 18TB drives.

The monthly scrubbing takes approximately 4 to 5 days.
The problem is that, since the scrubbing uses 100% of the disk, our backup system sometimes cannot finish the daily backups from out Clients.

So my question is: Is there any way to limit scrubbing to only 50% utilization?

Thanks in advance,
Christoph

 

[cheiss]

Hi,

this should be doable using some ZFS module parameters. Most interesting will probably be:
- zfs_top_maxinflight
- zfs_scrub_delay

But maybe there are also other parameters! I'd suggest just looking through them a bit yourself

 

[itwkpbs]

Hi,

Thanks for the quick response.

It seems that the mentioned parameters no longer exist in the newer versions of ZFS:
https://forum.proxmox.com/threads/lessen-scrub-impact-on-zfs-storage.110856/
They also don’t appear under "/sys/module/zfs/Parameters" on my system.

After further investigation, we believe we’ve identified the issue.
It appears there simply wasn’t enough available RAM.
We’ve freed up some memory now and will see if the next scrub runs faster.

Thanks again and a nice day
Christoph