rebuild-tree

[Larry Weldon <larry@welcoin.com>]

A client's production file server is set up using RAID-1 with 2 IDE
disks and reiserfs. The operating system is Mandrake 9.1. The system has
an APC 1050 SmartUPS on it - the place does have a history of power
glitches so _everything_ has a UPS.

Monday last I noticed the tape backup (I use tar) crashed at less than 1
minute with memory exhausted error. Examination showed a directory made
using a client machine as a 'backup' of the main job directory had an
error showing up as "cannot stat..." when running du. Since it was a
backup directory they just renamed it and tried to delete it using a DOS
shell. All the files and directories were successfully deleted except
the two offending files and their parent directories.

It took me all week to see what was wrong although it was plain...

After a successful backup, excluding the offending directory, I
unmounted and used reiserfsck --check which told me 1 item was badly
broken and to use reiserfsck --rebuild-tree which worked perfectly and
restored all the meta-data and files.

I would call that a nice job of recovering from some corruption. I did
not think to keep the output of the rebuild-tree function - I recall the
two bad files had some record of size 120 bytes (wrong) and it was reset
to 96 (correct).

I use reiserfs mostly because it was recommended by a friend. Now I find
out he has abandoned reiserfs because of:
http://www.wlug.org.nz/ReiserFS
which seems to be down right now so excerpt follows:
=======================================================================
Unfortunately, the tree structure used is also the weak point of 
ReiserFS: if any of it gets corrupted, chances are that much more data
will be affected than under traditional FileSystems. Rather than losing
a single file to corruption of an inode, you may lose almost the entire
contents of your disk if metadata close to the root of the BTree is
affected. Fortunately, the likelihood of this happening due to bugs has
been dramatically reduced in more recent version of the driver. Hardware
failure caused corruption is still a serious problem, though.
========================================================================

Now, I can't just stop using reiserfs and I don't want to. I think there
is great merit in it. So, first, with the limited info I have given,
what might have happened to create the problem and how likely might it
be to happen again? Secondly, what is the *real* hazard of corruption
_higher_up_ in the tree which the article says might blow away the whole
partition?

Thanks and regards.
-- 
Larry Weldon <larry@welcoin.com>