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From: Bill Davidsen <davidsen@tmr.com>
To: Helge Hafting <helgehaf@aitel.hist.no>
Cc: Neil Brown <neilb@suse.de>, Alan Cox <alan@lxorguk.ukuu.org.uk>,
	Arjan van de Ven <arjan@infradead.org>,
	Tomasz Torcz <zdzichu@irc.pl>,
	Thomas Glanzmann <sithglan@stud.uni-erlangen.de>,
	"Theodore Ts'o" <tytso@mit.edu>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: ext4 features (checksums)
Date: Wed, 05 Jul 2006 08:01:18 -0400	[thread overview]
Message-ID: <44ABAA0E.4000907@tmr.com> (raw)
In-Reply-To: <20060704124905.GB11458@aitel.hist.no>

Helge Hafting wrote:
> On Tue, Jul 04, 2006 at 01:19:11PM +0200, Krzysztof Halasa wrote:
>> Neil Brown <neilb@suse.de> writes:
>>
>>> With checksums - the filesystem is in a better position to:
>>>  - be selective about what is checksummed - no point checksumming
>>>    blocks that aren't part of any file.  Some blocks (highlevel
>>>    metadata) might always be checksummed, while other blocks
>>>    (regular data) might not if a 'fast' option was chosen.
>> The same applies to RAID - for example, why "synchronise" unused area?
>>
> Indeed.  RAID usually avoid checksumming unused area, it sums on write
> and you don't write "unused" stuff.  
> 
> Not syncing unused area is possible, if there was a way for raid resync
> to ask the fs what blocks are not in use.  I.e. get the
> free block list in disk block order.  Then raid resync could skip those.
> 
Current RAID code supports having a bitmap of dirty stripes, and can 
just sync those during recovery. I'm sure Neil could explain it better, 
but this is available without worrying about fs type. Now. Today.

-- 
Bill Davidsen <davidsen@tmr.com>
   Obscure bug of 2004: BASH BUFFER OVERFLOW - if bash is being run by a
normal user and is setuid root, with the "vi" line edit mode selected,
and the character set is "big5," an off-by-one errors occurs during
wildcard (glob) expansion.


  reply	other threads:[~2006-07-05 11:58 UTC|newest]

Thread overview: 119+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-07-01 16:33 ext4 features Thomas Glanzmann
2006-07-01 17:07 ` Tomasz Torcz
2006-07-01 17:47   ` Thomas Glanzmann
2006-07-01 18:09     ` Claudio Martins
2006-07-01 18:59       ` Thomas Glanzmann
2006-07-01 18:17     ` Tomasz Torcz
2006-07-03  9:44       ` Gabor Gombas
2006-07-03 20:22       ` Helge Hafting
2006-07-03 20:55         ` Tomasz Torcz
2006-07-03 21:01           ` Arjan van de Ven
2006-07-03 21:46             ` Jeff V. Merkey
2006-07-03 21:25               ` Diego Calleja
2006-07-03 22:17                 ` Alan Cox
2006-07-04 14:45                   ` Jan Engelhardt
2006-07-04 16:35                     ` Jeffrey V. Merkey
2006-07-04 18:52                       ` Jeff Garzik
2006-07-04 19:40                         ` Jeffrey V. Merkey
2006-07-05 13:35                       ` Lew Palm
2006-07-03 23:01                 ` Jeff V. Merkey
2006-07-04  9:14                 ` Benny Amorsen
2006-07-05  4:21                   ` Bill Davidsen
2006-07-05  5:13                     ` H. Peter Anvin
2006-07-05  5:45                       ` Jeffrey V. Merkey
2006-07-07 14:12                         ` Pavel Machek
2006-07-05 10:38                       ` Krzysztof Halasa
2006-07-07 14:10                     ` Pavel Machek
2006-07-07 17:45                       ` Krzysztof Halasa
2006-07-07 21:30                         ` Pavel Machek
2006-07-08 10:52                           ` Krzysztof Halasa
2006-07-08 10:55                             ` Pavel Machek
2006-07-08 11:19                               ` Krzysztof Halasa
2006-07-08 11:23                                 ` Pavel Machek
2006-07-08 18:45                                 ` Avi Kivity
2006-07-08 20:24                                   ` Krzysztof Halasa
2006-07-04  9:22                 ` Petr Tesarik
2006-07-04 11:35                   ` Peter Zijlstra
2006-07-04 11:55                     ` ext4 features (salvage) Petr Tesarik
     [not found]                       ` <80294dc60607040508l1022d164ybe0ba10858e54f0c@mail.gmail.com>
2006-07-04 12:31                         ` Petr Tesarik
2006-07-04 12:42                           ` Helge Hafting
2006-07-04 16:20                       ` Matthew Frost
2006-07-04 15:25                     ` ext4 features Pavel Machek
2006-07-05  4:10                     ` Bill Davidsen
2006-07-03 21:46               ` Valdis.Kletnieks
     [not found]                 ` <Pine.LNX.4.61.0607032354170.31747@yvahk01.tjqt.qr>
2006-07-04 14:37                   ` Kernel recycler [was: ext4 features] Jan Engelhardt
2006-07-04 11:14               ` ext4 features Krzysztof Halasa
2006-07-04 22:35               ` Frank van Maarseveen
2006-07-04 23:47                 ` Claudio Martins
2006-07-03 22:12             ` Alan Cox
2006-07-03 21:59               ` Arjan van de Ven
2006-07-03 23:31               ` ext4 features (checksums) Neil Brown
2006-07-04  1:03                 ` Jeff Garzik
2006-07-04  6:09                 ` Avi Kivity
2006-07-04  7:02                   ` Neil Brown
2006-07-04  8:26                     ` Avi Kivity
2006-07-05 11:56                       ` Bill Davidsen
2006-07-05 12:06                   ` Bill Davidsen
2006-07-05 12:19                     ` Avi Kivity
2006-07-08 17:54                       ` Bill Davidsen
2006-07-04  8:17                 ` Alan Cox
2006-07-04 11:08                   ` Thomas Glanzmann
2006-07-04 11:19                 ` Krzysztof Halasa
2006-07-04 12:49                   ` Helge Hafting
2006-07-05 12:01                     ` Bill Davidsen [this message]
2006-07-05 12:10                       ` Avi Kivity
2006-07-08 18:02                         ` Bill Davidsen
2006-07-06  0:36           ` Blatant layering violations (was Re: ext4 features) Valerie Henson
2006-07-06 12:15             ` Xavier Bestel
2006-07-06 17:06               ` Valdis.Kletnieks
2006-07-06 20:02             ` Tom Vier
2006-07-03 21:34         ` ext4 features Bill Davidsen
2006-07-03 21:50           ` Valdis.Kletnieks
2006-07-03 22:04             ` Bruce Ferrell
2006-07-04 14:48               ` Valdis.Kletnieks
2006-07-03 23:00             ` Bill Davidsen
2006-07-04 15:01               ` Valdis.Kletnieks
2006-07-05  2:40                 ` Bill Davidsen
2006-07-05  2:47                   ` Valdis.Kletnieks
2006-07-04 12:52             ` Helge Hafting
2006-07-06 15:12       ` Ric Wheeler
2006-07-06 17:05         ` Krzysztof Halasa
2006-07-06 17:27           ` Ric Wheeler
2006-07-06 20:52             ` Valdis.Kletnieks
2006-07-07 17:41               ` Krzysztof Halasa
2006-07-07 17:34             ` Krzysztof Halasa
2006-07-04  1:02 ` Theodore Tso
2006-07-04 19:16   ` Thomas Glanzmann
2006-07-04 19:30   ` Valdis.Kletnieks
2006-07-05 12:24   ` Bill Davidsen
2006-07-05 12:59     ` J. Bruce Fields
2006-07-05 13:17       ` Pádraig Brady
2006-07-05 19:33       ` Trond Myklebust
2006-07-05 21:22         ` Bill Davidsen
2006-07-05 21:42           ` Trond Myklebust
2006-07-08 21:04             ` Bill Davidsen
2006-07-10 20:08               ` Trond Myklebust
2006-07-10 22:37                 ` Bill Davidsen
2006-07-11  2:36                   ` Trond Myklebust
2006-07-21  3:10                     ` Bill Davidsen
2006-07-21 12:06                       ` Trond Myklebust
2006-07-21 14:36                         ` Theodore Tso
2006-07-21 19:02                           ` Trond Myklebust
2006-07-22 12:25                             ` Theodore Tso
2006-07-05 21:12       ` Bill Davidsen
2006-07-05 21:27         ` linux-os (Dick Johnson)
2006-07-05 21:41         ` J. Bruce Fields
2006-07-06  2:32           ` Bill Davidsen
2006-07-06  2:42             ` Nigel Cunningham
2006-07-06 12:43             ` Trond Myklebust
2006-07-07  2:15               ` Bill Davidsen
2006-07-07  2:30                 ` Trond Myklebust
2006-07-07  2:42                 ` Ric Wheeler
2006-07-07  2:46                   ` Trond Myklebust
2006-07-07  3:16                     ` Bill Davidsen
2006-07-07  8:09                       ` Bernd Petrovitsch
2006-07-07 14:56                       ` Trond Myklebust
2006-07-07 19:52                 ` Theodore Tso
2006-07-05 14:04   ` Avi Kivity
2006-07-04 14:36 ` Andi Kleen
2006-07-04 14:43   ` Thomas Glanzmann

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