[H-GEN] Idea for journalling filesystems

[Jason Parker-Burlingham]

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Stuart Longland <stuartl at longlandclan.hopto.org> writes:

> Jason Parker-Burlingham wrote:
> | Just this weekend I had to recover some valuable files from an ext2
> | disk which had suffered *major* filesystem corruption....
> 	So you might want to consider EXT3/ReiserFS.

FYI:  This was a client system.  I use XFS at home (and have done for
at least a year) and had been trying to persuade the client to pay me
to install a tape backup regime.  As is often the case we didn't solve
that problem in time.

As for Ext3/ReiserFS, neither of these options have the maturity of
XFS, which has been used for a very long time now in SGI's prodcuts.
In fact, as I recall from the last time I looked, XFS as a filesystem
is even older than the venerable Ext2.  It's this maturity that sold
me---in fact I even tried to get the aforementioned client to install
an XFS filesystem instead of ext3 back when I set up his SAMBA shares
a year ago.

> EXT3 should be an easy upgrade, it's possible to initialise an EXT3
> journal on an existing EXT2 filesystem using the e2fs tools.

I am not really looking for opinions on which journalling filesystem
to use, nor do I think that one should depend on mere journalling to
save themselves from a failing drive.

I think you were merely lucky that your dying disk did not simply take
out the journal and a superblock, and leave you with an unrecoverable
filesystem.

The point of journalling is to *speed up* filesystem checks, or in the
limit, to make that process wholly redundant.  It doesn't protect one
against drive errors---this is what scanning for bad blocks, various
RAID levels, and timely backups are for.

What I would like to know is whether a USB drive or some similar
technology would present a good block device to use as a journal which
lives off-disk.

jason
-- 
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