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Date: Wed, 26 May 2004 11:21:11 +0100
From: Ian Stirling <ian.stirling@mauve.plus.com>
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To: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
CC: Giuliano Pochini <pochini@denise.shiny.it>,
       "Eric D. Mudama" <edmudama@mail.bounceswoosh.org>,
       Tom Vier <tmv@comcast.net>, linux-kernel@vger.kernel.org
Subject: Re: Linux Kernel 2.6.6 IDE shutdown problems.
References: <BAY18-F105X7rz6AvEm0002622f@hotmail.com> <20040524171656.GA19026@bounceswoosh.org> <Pine.LNX.4.58.0405251101240.1197@denise.shiny.it> <200405251703.43000.bzolnier@elka.pw.edu.pl>
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Bartlomiej Zolnierkiewicz wrote:
> On Tuesday 25 of May 2004 11:05, Giuliano Pochini wrote:
> 
>>On Mon, 24 May 2004, Eric D. Mudama wrote:
>>
>>>Picture a nice fast drive doing 100 writes/second to the media... if
>>>you give it over 200 writes at a time, it'll occupy your 2 seconds.
>>>Newer drives with 8MB or larger buffers are certainly capable of
>>>caching a lot more than 200 writes...
>>
>>Quite unlikely. Usually disks have a big cache but it can hold a very
>>limited number of blocks. 8MB of cache is probably divided in 8 blocks
>>of 1MB each.
> 
> 
> No.

It is indeed likely that the worst case is around 16000 writes, which if
on seperate tracks may take over 30 seconds to complete if done individually.

However, it's likely that any drive designer with a clue would allocate a
couple of journal tracks, so that the write cache and two backup copies can
be stored for replay when the drive is powered on again.

Why do I suspect that some designers don't have clue, or haven't really thought
enough about this case.