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List:       freebsd-stable
Subject:    Re: 8.0-RELEASE/amd64 - full ZFS install - low read and write disk
From:       Dan Naumov <dan.naumov () gmail ! com>
Date:       2010-02-27 21:31:50
Message-ID: cf9b1ee01002271331p58f1ff53w8d61a7fd679e31d0 () mail ! gmail ! com
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Hello folks

A few weeks ago, there was a discussion started by me regarding
abysmal read/write performance using ZFS mirror on 8.0-RELEASE. I was
using an Atom 330 system with 2GB ram and it was pointed out to me
that my problem was most likely having both disks attached to a PCI
SIL3124 controller, switching to the new AHCI drivers didn't help one
bit. To reitirate, here are the Bonnie and DD numbers I got on that
system:

===================================================

Atom 330 / 2gb ram / Intel board + PCI SIL3124

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU /sec %CPU
         8192 21041 53.5 22644 19.4 13724 12.8 25321 48.5 43110 14.0 143.2 3.3

dd if=/dev/zero of=/root/test1 bs=1M count=4096
4096+0 records in
4096+0 records out
4294967296 bytes transferred in 143.878615 secs (29851325 bytes/sec) (28,4 mb/s)

===================================================

Since then, I switched the exact same disks to a different system:
Atom D510 / 4gb ram / Supermicro X7SPA-H / ICH9R controller (native).
Here are the updated results:

              -------Sequential Output-------- ---Sequential Input-- --Random--
              -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
         8192 30057 68.7 50965 36.4 27236 21.3 33317 58.0 53051 14.3 172.4  3.2

dd if=/dev/zero of=/root/test1 bs=1M count=4096
4096+0 records in
4096+0 records out
4294967296 bytes transferred in 54.977978 secs (78121594 bytes/sec) (74,5 mb/s)

===================================================

Write performance now seems to have increased by a factor of 2 to 3
and is now definately in line with the expected performance of the
disks in question (cheap 2TB WD20EADS with 32mb cache). Thanks to
everyone who has offered help and tips!


- Sincerely,
Dan Naumov
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