[OmniOS-discuss] Slow NFS writes in 151026

[Doug Hughes]

Evil tuning here:

https://www.solaris-cookbook.eu/solaris/solaris-10-zfs-evil-tuning-guide/

It's at the bottom. Where it says "Disabling the ZIL (Don't)"

I could see a lack of TRIM/erase support in background as a strong 
possibility caused by continuous use of blocks from the L2ARC over time.

Are you getting a high hit rate on your L2arc?

http://blog.harschsystems.com/2010/09/08/arcstat-pl-updated-for-l2arc-statistics/

If not, you might think about just dropping it all together and then

This, as old as it is, may not be accurate, but it doesn't give me high 
confidence that Trim support was added to illumos. Maybe it was and 
somebody else can chime in:

http://open-zfs.org/wiki/Features

zpool iostat -v <pool> may also be interesting for the l2arc/zil devices


On 8/23/2018 7:43 PM, Lee Damon wrote:
> (I've just changed from digest to regular subscription as I see there
> are messages relevant to this that I haven't received yet...)
>
> Doug, I'm not familiar with the evil zfs tuning wiki mechanism. I'll
> have to see if Google can help me find it.
>
> As for the ZIL+ L2ARC on the same SSD potentially being the problem,
> clearly I can't say with 100% certanty that it is not a problem however I
> have a second host (running 151022) with _exactly_ the same configuration
> of hard drives + split-SSD and NFS writes to that pool are fine.
>
> hvfs2 is ~18 months old but the chrup0 pool is a few months old.
>
> time cp -rp /misc/fs1test/004test /misc/hvfs2chru/omics1
>
> real    3m11.431s
> user    0m0.177s
> sys     0m28.030s
>
> time cp -rp /misc/fs1test/004test /misc/fs2test/omics1
>
> real    21m13.412s
> user    0m0.188s
> sys     0m28.678s
>
> nomad
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