Tracker in Edgy?

[Jamie McCracken]

John Richard Moser wrote:

> Want a bet?  I've seen JFS kill all of /usr; I've seen XF86Config get
> portions of Xorg.0.log in it on ReiserFS (how did THAT happen?!); and
> I've seen XFS and EXT3 straight truncate files that were in the middle
> of being resized when the power drops.
> 
> My worry is the database may be growing and suddenly get truncated to
> half its size or just thrown out by the file system.  Even journaled
> file systems will sometimes not know quite what to do; but they'll know
> what needs fixing right off.  They don't magically complete anything you
> do; they just clean up the file system by repairing meta-data, which may
> involve truncating files, freeing blocks, and unlinking.
> 
> This is an inherent hazard of having files that change size.  As long as
> you're making changes in-place, the file system is probably not going to
> have meta-data (besides mtime and atime, which are journaled perfectly)
> being rewritten; however, when a file is being resized, you can 1) wind
> out truncating it; 2) wind out deleting/unlinking it; or 3) wind out
> filling it with zeroes (if the FS doesn't know the original size or
> allocated blocks, it should fill it with zeroes to avoid leaking
> previously deleted, possibly privileged data).

You can tell Ext3 and ReiserFS to journal data as well as metadata and 
in those cases it should protect you from this. (use data=journal in 
/etc/fstab).

Of course if there are bugs in the FS implementation then problems can 
occur and I suspect that might be why some of the newer ones (like JFS) 
have problems too.

> 
>> also mysql has an excellent reputation with regards to the integrity of
>> its databases.
>>
> 
> I've heard exactly the contrary (MySQL can be easily shredded by a
> single power drop, and its recovery routines don't work most of the
> time); but I haven't seen a problem myself.  Like I said, I'm more
> worried about the underlying file system interacting with the database.

On dodgy filesystems thats true but try a jounalised data and metadata 
FS and it should be extremely robust.

-- 
Mr Jamie McCracken
http://jamiemcc.livejournal.com/