Re: Speed improvements in ZFS

From: Alexander Leidinger <Alexander_at_Leidinger.net>
Date: Fri, 15 Sep 2023 11:55:20 UTC
Am 2023-09-15 13:40, schrieb George Michaelson:

> Not wanting to hijack threads I am interested if any of this can 
> translate back up tree and make Linux ZFS faster.
> 
> And, if there are simple sysctl tuning worth trying in large (tb) 
> memory model pre 14 FreeBSD systems with slow zfs. Older freebsd alas.

The current part of the discussion is not really about ZFS (I use a lot 
of nullfs on top of ZFS). So no to the first part.

The tuning I did (maxvnodes) doesn't really depend on the FreeBSD 
version, but on the number of files touched/contained in the FS. The 
only other change I made is updating the OS itself, so this part doesn't 
apply to pre 14 systems.

If you think your ZFS (with a large ARC) is slow, you need to review 
your primary cache settings per dataset, check the arcstats, and maybe 
think about a 2nd level arc on fast storage (cache device on nvm or 
ssd). IF you have a read-once workload, nothing of this will help. So 
all depends on your workload.

Bye,
Alexander.

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