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From: Pavel Machek <pavel@ucw.cz>
To: Jeff Garzik <jgarzik@pobox.com>
Cc: Hans Reiser <reiser@namesys.com>,
	"Mudama, Eric" <eric_mudama@Maxtor.com>,
	"'Norman Diamond'" <ndiamond@wta.att.ne.jp>,
	"'Wes Janzen '" <superchkn@sbcglobal.net>,
	"'Rogier Wolff '" <R.E.Wolff@BitWizard.nl>,
	"'John Bradford '" <john@grabjohn.com>,
	linux-kernel@vger.kernel.org, nikita@namesys.com,
	"'Pavel Machek '" <pavel@ucw.cz>,
	"'Justin Cormack '" <justin@street-vision.com>,
	"'Vitaly Fertman '" <vitaly@namesys.com>,
	"'Krzysztof Halasa '" <khc@pm.waw.pl>
Subject: Re: Blockbusting news, results get worse
Date: Tue, 28 Oct 2003 02:21:43 +0100	[thread overview]
Message-ID: <20031028012143.GA427@elf.ucw.cz> (raw)
In-Reply-To: <3F9D7666.6010504@pobox.com>

Hi!

> >>or put it under heavy write workload and remove
> >>power.
> >>
> >Can you tell us more about what really happens to disk drives when the 
> >power is cut while a block is being written?  We engage in a lot of 
> >uninformed speculation, and it would be nice if someone who really knows 
> >told us....
> >
> >Do drives have enough capacitance under normal conditions to finish 
> >writing the block?  Does ECC on the drive detect that the block was bad 
> >and so we don't need to detect it in the FS?
> 
> 
> Does it really matter to speculate about this?
> 
> If you don't FLUSH CACHE, you have no guarantees your data is on the 
> platter.

Well, even without FLUSH CACHE, you can expect that sector being
writen during powerfail either contains old data *or* new data.

If sector can become unreadable after powerfail, I guess journaling
people would like to know, and if powerfail may mean adjacent (or even
unrelated?) sectors to be damaged, everyone needs to know...
								Pavel
-- 
When do you have a heart between your knees?
[Johanka's followup: and *two* hearts?]

  parent reply	other threads:[~2003-10-28  1:22 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-10-27 17:43 Blockbusting news, results get worse Mudama, Eric
2003-10-27 18:48 ` Hans Reiser
2003-10-27 19:47   ` Jeff Garzik
2003-10-27 20:03     ` John Bradford
2003-10-29 20:01       ` Pavel Machek
2003-10-30  8:30         ` John Bradford
2003-10-28  1:21     ` Pavel Machek [this message]
2003-10-28 12:54       ` Krzysztof Halasa
  -- strict thread matches above, loose matches on Subject: below --
2003-10-29 20:11 Mudama, Eric
2003-10-27 18:06 Mudama, Eric
2003-10-27 19:18 ` Andre Hedrick
2003-10-27 13:07 Samium Gromoff
2003-10-26 22:12 Mudama, Eric
2003-10-26 18:33 Mudama, Eric
2003-10-26 22:03 ` Andre Hedrick
2003-10-27  9:34 ` Norman Diamond
2003-10-27 10:23   ` Jan-Benedict Glaw
2003-10-27 23:31   ` Jason Lunz
2003-10-28 20:56   ` Hans Reiser
2003-10-26  7:37 Norman Diamond
2003-10-26 10:39 ` John Bradford
2003-10-26  9:41   ` Pavel Machek
2003-10-26 11:38   ` Norman Diamond
2003-10-26 11:56     ` Pavel Machek
2003-10-26 12:06     ` Hans Reiser
2003-10-26 13:59     ` Krzysztof Halasa

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