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SubjectRe: questions about io scheduler
Timothy Miller wrote:
>
>
> Mike Fedyk wrote:
>
>> Nick Piggin wrote:
>>
>>>
>>>
>>> Kyle Wong wrote:
>>>
>>>> 2. Does io scheduler works with md RAID? Correct me if I'm wrong,
>>>> io-schedular <--> md driver <--> harddisks.
>>>>
>>>>
>>>
>>> It goes md driver -> io schedulers -> hard disks.
>>
>>
>>
>> There is an IO scheduler per disk.
>>
>> So MD submits the data to each disk through the IO scheduler.
>>
>> This allows you to have the heads on each disk in the array at
>> different locations, and helps keep response times lower for seeky loads.
>
>
> Say you've got a RAID1. In this case, MD could send the read request to
> either device. How does it decide which one to use?

The one with the drive head closest to the data.
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