From: Hans Reiser <reiser@namesys.com>
To: Mike Fedyk <mfedyk@matchmail.com>
Cc: Andrew Morton <akpm@osdl.org>,
reiserfs-list@namesys.com, linux-kernel@vger.kernel.org
Subject: Re: precise characterization of ext3 atomicity
Date: Thu, 04 Sep 2003 22:37:10 +0400 [thread overview]
Message-ID: <3F578656.60005@namesys.com> (raw)
In-Reply-To: <20030904181540.GC13676@matchmail.com>
Mike Fedyk wrote:
>On Thu, Sep 04, 2003 at 08:25:18PM +0400, Hans Reiser wrote:
>
>
>>In data=journal and data=ordered modes ext3 also guarantees that the
>>metadata will be committed atomically with the data they point to. However
>>ext3 does not provide user data atomicity guarantees beyond the scope of a
>>single filesystem disk block (usually 4 kilobytes). If a single write()
>>spans two disk blocks it is possible that a crash partway through the write
>>will result in only one of those blocks appearing in the file after
>>recovery.
>>
>>
>
>And how does reiser4 do this without changing the userspace apps?
>
We don't. We just make the hovercraft, we don't force you to go over
the water.....
>
>Most files are written with several write() calls, so even if each call is
>atomic, your entire file will not be there.
>
>Also, ext3 could claim the same atomicity if it only updated meta-data on
>write() call boundaries, instead of block boundaries.
>
>
>
>
--
Hans
next prev parent reply other threads:[~2003-09-04 18:39 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-04 14:20 precise characterization of ext3 atomicity Hans Reiser
2003-09-04 15:55 ` Andrew Morton
2003-09-04 15:59 ` Hans Reiser
2003-09-04 16:12 ` Andrew Morton
2003-09-04 16:25 ` Hans Reiser
2003-09-04 18:15 ` Mike Fedyk
2003-09-04 16:05 ` Antonio Vargas
2003-09-04 18:37 ` Hans Reiser [this message]
2003-09-04 19:12 ` Mike Fedyk
2003-09-04 21:03 ` Hans Reiser
2003-09-04 19:28 ` Andreas Dilger
2003-09-04 21:32 ` Hans Reiser
2003-09-04 22:03 ` Andreas Dilger
2003-09-05 13:47 ` Chris Mason
2003-09-09 13:09 ` Pavel Machek
2003-09-09 19:21 ` Gábor Lénárt
2003-09-09 19:43 ` Mike Fedyk
2003-09-04 20:16 ` Daniel Phillips
2003-09-04 20:10 ` Andrew Morton
2003-09-04 21:08 ` Daniel Phillips
2003-09-04 21:39 ` Hans Reiser
2003-09-04 21:59 ` Daniel Phillips
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