[LUNI] file system limitations

[Steven Lembark]

-- Erik Lickerman <elickerman at ameritech.net>

> What would be the consequence of this instability?  System crash?  Loss of
> data from the hard-drive?

Depending on how often the files are updated, probably
nothing. A journanling filesystem will cache metadata
but you are still fried if you loose whatever's in the
I/O cache. With this many small files being opened and
closed quickly you can auto-flush them and be done with
it. A UPS might help -- until someone hits the power cord
with a mop or drips blood onto some contacts.

If the filesystem will be updated frequently then journalling
will be a performance penalty -- you are basically amortizing
the cost of fsck over the uptime of the system. Problem there
is that with this many files, if their metadata gets modified
frequently then you can have a serious performance issue with
journalling. Comparing it to the time you would spend fscking
the filesystem on crashes it may not pay in the end.

If the file contents will be modified frequently then you
should seriuosly consider using a database for your database
rather than the filesystem. The normal commit mechanism of a
real RDBMS will handle all of this for you with probably less
programming overall (e.g., using DBI with varchar's).




--
Steven Lembark                               2930 W. Palmer
Workhorse Computing                       Chicago, IL 60647
                                            +1 800 762 1582