Re: [ext4] Documentation patch

From: Eric Sandeen
Date: Mon Dec 01 2008 - 12:59:46 EST

Christoph Hellwig wrote:
> On Mon, Dec 01, 2008 at 05:46:56PM +0100, Harald Arnesen wrote:
>> So when comparing with a metadata-only journalling filesystem, such
>> - as ext3, use `mount -o data=writeback'. And you might as well use
>> + as jfs or xfs, use `mount -o data=writeback'. And you might as well use
> data=ordered comes closest to what xfs does for quite a long time..

Agreed; that whole bit which mentions other filesystem comparisons
should probably be stricken, unless it can be
proven/demonstrated/substantiated that ext3 really does "offer higher
data integrity guarantees than most" at this point.

data=ordered ensures that stale data won't be exposed on a crash; xfs
won't do this (it'd be a security bug) and I'd be surprised if jfs or
reiserfs do either. And it probably *should* be mentioned that
data=writeback bears this risk.

And until ext3 turns on barriers by default, I don't think it's fair to
talk too much about integrity guarantees. :)

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