From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
Subject: Re: RBD fio Performance concerns
Date: Fri, 23 Nov 2012 11:49:10 +0100
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To: Alexandre DERUMIER <aderumier@odiso.com>
Cc: Mark Nelson <mark.nelson@inktank.com>, ceph-devel <ceph-devel@vger.kernel.org>, Mark Kampe <mark.kampe@inktank.com>, =?UTF-8?B?U8OpYmFzdGllbiBIYW4=?= <han.sebastien@gmail.com>

Am 23.11.2012 11:47, schrieb Alexandre DERUMIER:
>>> when i switch the journal to the OSD Disk seperate partiton on each disk
>>> (/dev/sdX1 for journal 1GB and /dev/sdX2 for OSD) i go down from 23.000
>>> iops to 200 iops random 4k.
> O_o , that's seem crazy...
> Are you sure that your partitions are correctly aligned ? (starting first partition at sector 2048 is best for ssd)

Model: ATA INTEL SSDSC2CW24 (scsi)
Disk /dev/sdb: 468862128s
Sector size (logical/physical): 512B/512B
Partition Table: gpt

Number  Start     End         Size        File system  Name  Flags
  1      2048s     2342911s    2340864s    xfs          pri
  2      2342912s  468860927s  466518016s  xfs          pri

Stefan