Re: iostat with raid device...

[Linux Raid Study <linuxraid.study@xxxxxxxxx>]

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 <roberto@xxxxxxxxxxxxx> wrote:
> another question... why md have more tps? disk elevators? sector size?
>
> 2011/4/8 Linux Raid Study <linuxraid.study@xxxxxxxxx>:
>> 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 ÂBlksWrtn/sec?
>> My strip size is 1MB.
>>
>> thanks for any pointers...
>>
>> avg-cpu: Â%user  %nice %system %iowait Â%steal  %idle
>> Â Â Â Â Â 0.02 Â Â0.00 Â Â0.34 Â Â0.03 Â Â0.00 Â 99.61
>>
>> Device:      Âtps  Blk_read/s  Blk_wrtn/s  Blk_read  Blk_wrtn
>> sda        1.08    247.77    338.73  37478883  51237136
>> sda1 Â Â Â Â Â Â Â1.08 Â Â Â 247.77 Â Â Â 338.73 Â 37478195 Â 51237136
>> sdb        1.08    247.73    338.78  37472990  51245712
>> sdb1 Â Â Â Â Â Â Â1.08 Â Â Â 247.73 Â Â Â 338.78 Â 37472302 Â 51245712
>> sdc        1.10    247.82    338.66  37486670  51226640
>> sdc1 Â Â Â Â Â Â Â1.10 Â Â Â 247.82 Â Â Â 338.66 Â 37485982 Â 51226640
>> sdd        1.09    118.46    467.97  17918510  70786576
>> sdd1 Â Â Â Â Â Â Â1.09 Â Â Â 118.45 Â Â Â 467.97 Â 17917822 Â 70786576
>> md0 Â Â Â Â Â Â Â65.60 Â Â Â 443.79 Â Â Â1002.42 Â 67129812 Â151629440
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>
>
>
> --
> Roberto Spadim
> Spadim Technology / SPAEmpresarial
>
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