From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linux Raid Study Subject: Re: iostat with raid device... Date: Fri, 8 Apr 2011 15:10:45 -0700 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Roberto Spadim Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Thanks for pointing this out...I did observe this but forgot to mention in the email... Can someone give some insight into this. Thanks. On Fri, Apr 8, 2011 at 3:05 PM, Roberto Spadim = wrote: > another question... why md have more tps? disk elevators? sector size= ? > > 2011/4/8 Linux Raid Study : >> Hello, >> >> I have a raid device /dev/md0 based on 4 devices sd[abcd]. >> >> When I write 4GB to /dev/md0, I see following output from iostat... >> >> Ques: >> Shouldn't I see write/sec to be same for all four drives? Why does >> /dev/sdd always have higher value for =C2=A0BlksWrtn/sec? >> My strip size is 1MB. >> >> thanks for any pointers... >> >> avg-cpu: =C2=A0%user =C2=A0 %nice %system %iowait =C2=A0%steal =C2=A0= %idle >> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 0.02 =C2=A0 =C2=A00.00 =C2=A0 =C2= =A00.34 =C2=A0 =C2=A00.03 =C2=A0 =C2=A00.00 =C2=A0 99.61 >> >> Device: =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0tps =C2=A0 Blk_read= /s =C2=A0 Blk_wrtn/s =C2=A0 Blk_read =C2=A0 Blk_wrtn >> sda =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 1.08 =C2=A0 =C2= =A0 =C2=A0 247.77 =C2=A0 =C2=A0 =C2=A0 338.73 =C2=A0 37478883 =C2=A0 51= 237136 >> sda1 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A01.08 =C2=A0 =C2= =A0 =C2=A0 247.77 =C2=A0 =C2=A0 =C2=A0 338.73 =C2=A0 37478195 =C2=A0 51= 237136 >> sdb =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 1.08 =C2=A0 =C2= =A0 =C2=A0 247.73 =C2=A0 =C2=A0 =C2=A0 338.78 =C2=A0 37472990 =C2=A0 51= 245712 >> sdb1 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A01.08 =C2=A0 =C2= =A0 =C2=A0 247.73 =C2=A0 =C2=A0 =C2=A0 338.78 =C2=A0 37472302 =C2=A0 51= 245712 >> sdc =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 1.10 =C2=A0 =C2= =A0 =C2=A0 247.82 =C2=A0 =C2=A0 =C2=A0 338.66 =C2=A0 37486670 =C2=A0 51= 226640 >> sdc1 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A01.10 =C2=A0 =C2= =A0 =C2=A0 247.82 =C2=A0 =C2=A0 =C2=A0 338.66 =C2=A0 37485982 =C2=A0 51= 226640 >> sdd =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 1.09 =C2=A0 =C2= =A0 =C2=A0 118.46 =C2=A0 =C2=A0 =C2=A0 467.97 =C2=A0 17918510 =C2=A0 70= 786576 >> sdd1 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A01.09 =C2=A0 =C2= =A0 =C2=A0 118.45 =C2=A0 =C2=A0 =C2=A0 467.97 =C2=A0 17917822 =C2=A0 70= 786576 >> md0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A065.60 =C2=A0 =C2= =A0 =C2=A0 443.79 =C2=A0 =C2=A0 =C2=A01002.42 =C2=A0 67129812 =C2=A0151= 629440 >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-raid= " in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at =C2=A0http://vger.kernel.org/majordomo-info.h= tml >> > > > > -- > Roberto Spadim > Spadim Technology / SPAEmpresarial > -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html