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From: Nuno Silva <nuno.silva@vgertech.com>
To: Torben Frey <kernel@mailsammler.de>
Cc: linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Re: Horrible drive performance under concurrent i/o jobs (dlh problem?)
Date: Fri, 20 Dec 2002 01:47:37 +0000	[thread overview]
Message-ID: <3E0276B9.40001@vgertech.com> (raw)
In-Reply-To: <3E01D7D7.2070201@mailsammler.de>

Hello!

Torben Frey wrote:

[..snip..]

> watching "vmstat 1" in another window - and this is what surprised me:
> when I stopped the copy job, there were 22 more seconds when data was
> still written to the backup software raid. Is this a hint where the
> problem could be? I have the same "feature" when I write to my 3ware.
> 

[..snip..]

AFAIK, this is because you have some GB of memory (RAM) that are beeing 
used as disk-cache. It took 22 seconds for the cached writes-to-disk 
being flushed to the device.

If 22 seconds is too much for the amount of cached disk-writes is 
another story :)

Maybe 3ware controllers are slow with many disks? Try the same with only 
3 disks to eliminate this variable.

Regards,
Nuno Silva


  reply	other threads:[~2002-12-20  1:37 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2002-12-19 14:29 Horrible drive performance under concurrent i/o jobs (dlh problem?) Torben Frey
2002-12-20  1:47 ` Nuno Silva [this message]
2002-12-27 13:04   ` Torben Frey
2002-12-20 14:27 ` Roger Larsson
  -- strict thread matches above, loose matches on Subject: below --
2002-12-18 21:10 Con Kolivas
2002-12-18 22:16 ` Torben Frey
2002-12-18 22:37   ` Andrew Morton
2002-12-18 23:30     ` Torben Frey
2002-12-18 23:46       ` Andrew Morton
2002-12-18 22:40   ` Torben Frey
2002-12-18 19:06 Torben Frey
2002-12-20 20:40 ` Joseph D. Wagner
2002-12-20 22:25   ` David Lang
2002-12-21  6:00     ` Joseph D. Wagner
2002-12-23  1:29       ` David Lang
2002-12-24  9:18       ` Roy Sigurd Karlsbakk
2002-12-24 17:21         ` jw schultz
2002-12-24 21:00           ` Jeremy Fitzhardinge
2002-12-25  1:34           ` Rik van Riel
2002-12-25  2:02           ` jw schultz
2002-12-25  3:41           ` Barry K. Nathan
2002-12-23 17:48   ` Krzysztof Halasa
2002-12-23 18:13 ` Denis Vlasenko

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