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

[Caza, Aaron]

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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