Verification Job is very slow

[franconovik]

Hello,
I am using Proxmox Backup Server.
I am wondering how "Verification Job" works.
I let it start at 23.30 and next day in the morning at 10.00 it is still running.
It should check 8 disks total of 800GB.
What can I monitor or do to spped up this process ?
Garbage Collection instead starts at 24.00 and find also this one running in the morning at 10.00 ?
Very slow.
What can I do ?


Thanks
/Franco

 

[meyergru]

For starters, do not let both disk-intensive tasks run at the same time. Use a weekly schedule and let them run on different weekdays.

 

[franconovik]

Sorry, but what does It mean?
Verify job should start for example at 23.30 and garage Collection at 5.00 in the morning?

 

[meyergru]

No. Start your jobs on Monday and Thursday, for example. A verify job, a garbage collection or a ZFS scrub can easily take more than one day even if run by itself. And if two jobs are run at the same time, they cannot use sequential access, but cause disk thrashing because of switching back and forth between the tasks. This can lead to each individual job running magnitudes slower. It is unneccesary to run either a verify or a garbage collect every day.

 

[franconovik]

Ok thanks

 

[UdoB]

Very slow.

You did not tell us what kind of storage you are using.

If it is rotating rust then yes, that's expected. To verify the stored data each and every chunk needs to be read, the checksum gets calculated and compared with another copy. This requires a lot of physical head movements... which is inherently slow.

What can I do ?

In the case of HDDs follow the recommendation and use SSDs instead: https://pbs.proxmox.com/docs/installation.html#recommended-server-system-requirements

There are ways to optimize storage to some degree, e.g. adding a fast "Special Device" to a slow ZFS pool - before filling it up.