From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Spadim Subject: Re: iostat with raid device... Date: Fri, 8 Apr 2011 19:05:01 -0300 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Linux Raid Study Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids 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 =A0BlksWrtn/sec? > My strip size is 1MB. > > thanks for any pointers... > > avg-cpu: =A0%user =A0 %nice %system %iowait =A0%steal =A0 %idle > =A0 =A0 =A0 =A0 =A0 0.02 =A0 =A00.00 =A0 =A00.34 =A0 =A00.03 =A0 =A00= =2E00 =A0 99.61 > > Device: =A0 =A0 =A0 =A0 =A0 =A0tps =A0 Blk_read/s =A0 Blk_wrtn/s =A0 = Blk_read =A0 Blk_wrtn > sda =A0 =A0 =A0 =A0 =A0 =A0 =A0 1.08 =A0 =A0 =A0 247.77 =A0 =A0 =A0 3= 38.73 =A0 37478883 =A0 51237136 > sda1 =A0 =A0 =A0 =A0 =A0 =A0 =A01.08 =A0 =A0 =A0 247.77 =A0 =A0 =A0 3= 38.73 =A0 37478195 =A0 51237136 > sdb =A0 =A0 =A0 =A0 =A0 =A0 =A0 1.08 =A0 =A0 =A0 247.73 =A0 =A0 =A0 3= 38.78 =A0 37472990 =A0 51245712 > sdb1 =A0 =A0 =A0 =A0 =A0 =A0 =A01.08 =A0 =A0 =A0 247.73 =A0 =A0 =A0 3= 38.78 =A0 37472302 =A0 51245712 > sdc =A0 =A0 =A0 =A0 =A0 =A0 =A0 1.10 =A0 =A0 =A0 247.82 =A0 =A0 =A0 3= 38.66 =A0 37486670 =A0 51226640 > sdc1 =A0 =A0 =A0 =A0 =A0 =A0 =A01.10 =A0 =A0 =A0 247.82 =A0 =A0 =A0 3= 38.66 =A0 37485982 =A0 51226640 > sdd =A0 =A0 =A0 =A0 =A0 =A0 =A0 1.09 =A0 =A0 =A0 118.46 =A0 =A0 =A0 4= 67.97 =A0 17918510 =A0 70786576 > sdd1 =A0 =A0 =A0 =A0 =A0 =A0 =A01.09 =A0 =A0 =A0 118.45 =A0 =A0 =A0 4= 67.97 =A0 17917822 =A0 70786576 > md0 =A0 =A0 =A0 =A0 =A0 =A0 =A065.60 =A0 =A0 =A0 443.79 =A0 =A0 =A010= 02.42 =A0 67129812 =A0151629440 > -- > 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 =A0http://vger.kernel.org/majordomo-info.html > --=20 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