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Re: extremely slow write performance plaintext

To: Michael Monnerie <michael.monnerie@xxxxxxxxxxxxxxxxxxx>
Subject: Re: extremely slow write performance plaintext
From: Cory Coager <ccoager@xxxxxxxxxxxxxxx>
Date: Tue, 25 Jan 2011 09:27:23 -0500
Banner: Set
Cc: xfs@xxxxxxxxxxx, Stan Hoeppner <stan@xxxxxxxxxxxxxxxxx>
In-reply-to: <201101250721.14716@xxxxxx>
Organization: Davis Vision
References: <3205_1294953756_4D2F6D1C_3205_1943_1_4D2F6D1C.2060409@xxxxxxxxxxxxxxx> <4D30C7F3.3040105@xxxxxxxxxxxxxxxxx> <1779_1295360207_4D35A0CF_1779_747_1_4D35A0CF.9050503@xxxxxxxxxxxxxxx> <201101250721.14716@xxxxxx>
User-agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.13) Gecko/20101208 Lightning/1.0b2 Thunderbird/3.1.7
On 01/25/2011 01:21 AM, Michael Monnerie wrote:
You're getting 40MB/s write speed and says that's fine? I get more
performance from a single SATA desktop drive. Your setup seems to suck
extremely somewhere.

It already starts with your dd speed. I started it on a virtualized VM
on an old, overloaded server and get:

# dd if=/dev/zero of=test.dd bs=1k count=1M
1048576+0 Datensätze ein
1048576+0 Datensätze aus
1073741824 Bytes (1,1 GB) kopiert, 10,9992 s, 97,6 MB/s

This is a hardware RAID 6 with just 8x 10krpm WD SATA drives. Try to
look into general I/O problems. Maybe you can try to boot from an actual
linux CD with kernel>2.6.30 to see if that helps performance.

Maybe one or more disks in your array are dead and the controller is
crying for replacement?
I just checked the array configuration utility, no drives are dead. Unfortunately this server is in production and I am not physical next to the machine so I won't be able to test with a LiveCD.



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