From mboxrd@z Thu Jan 1 00:00:00 1970 From: Peter Rabbitson Subject: Re: Fastest Chunk Size w/XFS For MD Software RAID = 1024k Date: Thu, 28 Jun 2007 10:36:23 +0200 Message-ID: <46837307.20005@rabbit.us> References: <46832E60.9000006@rabbit.us> <46837056.4050306@rabbit.us> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Justin Piszcz Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Justin Piszcz wrote: > > On Thu, 28 Jun 2007, Peter Rabbitson wrote: > >> Interesting, I came up with the same results (1M chunk being superior) >> with a completely different raid set with XFS on top: >> >> ... >> >> Could it be attributed to XFS itself? >> >> Peter >> > > Good question, by the way how much cache do the drives have that you are > testing with? > I believe 8MB, but I am not sure I am looking at the right number: root@Arzamas:~# hdparm -i /dev/sda /dev/sda: Model=aMtxro7 2Y050M , FwRev=AY5RH10W, SerialNo=6YB6Z7E4 Config={ Fixed } RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=4 BuffType=DualPortCache, BuffSize=7936kB, MaxMultSect=16, MultSect=?0? CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=268435455 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120} PIO modes: pio0 pio1 pio2 pio3 pio4 DMA modes: mdma0 mdma1 mdma2 UDMA modes: udma0 udma1 udma2 udma3 udma4 udma5 AdvancedPM=yes: disabled (255) WriteCache=enabled Drive conforms to: ATA/ATAPI-7 T13 1532D revision 0: ATA/ATAPI-1 ATA/ATAPI-2 ATA/ATAPI-3 ATA/ATAPI-4 ATA/ATAPI-5 ATA/ATAPI-6 ATA/ATAPI-7 * signifies the current active mode root@Arzamas:~# 1M chunk consistently delivered best performance with: o A plain dumb dd run o bonnie o two bonnie threads o iozone with 4 threads My RA is set at 256 for the drives and 16384 for the array (128k and 8M respectively)