FreeBSD10 Stable + ZFS + PostgreSQL + SSD performance drop < 24 hours

[Allan Jude]

On 2017-06-14 13:11, Caza, Aaron wrote:
> Further to this:
> 
> I've now tested FreeBSD 10.3-RELEASE-p19 and FreeBSD 11.0-STABLE #0 r307264M, both of which suffer the same degraded performance.
> 
> test$ uname -a
> FreeBSD xyz.com 10.3-RELEASE-p19 FreeBSD 10.3-RELEASE-p19 #0 r319904M: Tue Jun 13 12:38:29 MDT 2017     aaronc at WFT:XYZ  amd64
> test$ uptime
> 10:15AM  up 21:09, 2 users, load averages: 1.00, 1.14, 1.30
> test$ dd if=/testdb/test of=/dev/null bs=1m
> 16000+0 records in
> 16000+0 records out
> 16777216000 bytes transferred in 200.379127 secs (83727363 bytes/sec)
> 
> After reboot:
> test$ dd if=/testdb/test of=/dev/null bs=1m
> 16000+0 records in
> 16000+0 records out
> 16777216000 bytes transferred in 23.213040 secs (722749623 bytes/sec)
> 
> Same Intel Xeon E31240 with 8GB ram and 2x Samsung 850 Pro 256GB SSDs as before.
> 
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> 

Can you do the same test, but grab the memory lines from top(1) before
and after each of those two runs.

I am guessing the ARC is being squeezed out by PostgreSQL, because you
have so little RAM.

-- 
Allan Jude

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