Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian
Administration)
Posted Apr 26, 2006 16:05 UTC (Wed) by
Duncan (guest, #6647)
In reply to:
Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian
Administration) by sbergman27
Parent article:
Filesystems (ext3, reiser, xfs, jfs) comparison on Debian Etch (Debian
Administration)
> What this article leaves out... what most *every*
> fs benchmark article leaves out is the fact that
> EXT3 gives you a much greater level of journalling
> protection than the others by default. By default,
> EXT3 gives you metadata journalling and ordered
> writes of metadata and data. The others only give
> you metadata journalling by default. And, of the
> others, only reiserfs gives you the option of
> anything higher.
> Reiserfs and EXT3 offer full data journalling.
> EXT3 offers an intermediate option called "ordered"
> mode. [...] This is (wisely in my opinion) EXT3's
> default.
Actually, reiserfs offers ordered mode as well. It didn't originally, but
Chris Mason's patch adding the functionality was merged into to the
mainline kernel before full data journalling for reiserfs was added. (A
google turns up this changelog for 2.6.6-rc1:
http://lwn.net/Articles/80719/ ) It became the default either at that
time or soon thereafter.
That said, if you didn't know it was there (I knew in part due to LWN
coverage), it would be and remains very hard to notice that it's now using
ordered. The output at filesystem mount doesn't mention the fact, and of
course being the default, there's no indication in fstab. One has to look
quite carefully at the dmesg output for the mount to notice it. It should
have a line something like (from my boot log, md_d1p1 of course indicates
partitioned RAID):
ReiserFS: md_d1p1: using ordered data mode
I remember looking to see that I was using ordered shortly after
installing and booting that kernel, and wondering why it didn't
mention "ordered mode" in the mount output. I certainly would have missed
it too, had I not known it was there. To your credit, you knew about the
later journalled mode reiserfs patches, but you apparently missed the
ordered mode patches, and that just as with ext3, that's now the default
for reiserfs.
Oh, for anyone interested, those patches /did/ make reiserfs far more
stable. I had a bout with some bad memory during which I was crashing
quite frequently -- and usually under high load and disk activity at
that -- and reiserfs came thru with flying colors! =8^) That's far better
than it did when I first started using it, back in the bad old early 2.4
days.
Duncan
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