From: Bill Davidsen <davidsen@tmr.com>
To: Mike Fedyk <mfedyk@matchmail.com>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: questions about io scheduler
Date: Tue, 09 Mar 2004 15:22:32 -0500 [thread overview]
Message-ID: <404E2788.1060108@tmr.com> (raw)
In-Reply-To: <1wxyd-1WX-1@gated-at.bofh.it>
Mike Fedyk wrote:
> 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.
Or hopefully the one not in use if one is busy...
next parent reply other threads:[~2004-03-09 20:17 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <1wjF1-2yG-19@gated-at.bofh.it>
[not found] ` <1wk7X-31w-1@gated-at.bofh.it>
[not found] ` <1wwCd-Pi-5@gated-at.bofh.it>
[not found] ` <1wx5r-1qI-9@gated-at.bofh.it>
[not found] ` <1wxyd-1WX-1@gated-at.bofh.it>
2004-03-09 20:22 ` Bill Davidsen [this message]
2004-03-05 9:22 questions about io scheduler Kyle Wong
2004-03-05 9:20 ` Nick Piggin
2004-03-05 22:57 ` Mike Fedyk
2004-03-05 23:49 ` Timothy Miller
2004-03-05 23:58 ` Mike Fedyk
2004-03-05 9:20 ` Jens Axboe
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