[Lustre-discuss] Lustre & SQLite

[Andreas Dilger]

On Feb 11, 2009  22:19 +0100, Michal Wesolowski wrote:
> I'm trying to determine whether SQLite will properely work on Lustre. From a 
> quick search it seems that some people use it successfully using 
> flock/localflock mount option. But I have doubts.
> I'm interested in 2 scenarios:
> - SQLite works properely for single Lustre node.
> - SQLite files are accessed simultanously by processes on more than one node.

I think that is only between processes on the same node.  I think accessing
SQLite between different processes on different nodes might result in file
corruption by SQLite itself, regardless of the locking by Lustre.

If you want to test this, you definitely need to mount all clients with
"-o flock" so the locking is coherent across all clients.

> In SQLite documentation (http://www.sqlite.org/lockingv3.html) there is 
> statement that this db engine uses advisory locks to protect shared date.


   6.0 How To Corrupt Your Database Files

   SQLite uses POSIX advisory locks to implement locking on Unix...
   Your best defense is to not use SQLite for files on a network filesystem. 

Cheers, Andreas
--
Andreas Dilger
Sr. Staff Engineer, Lustre Group
Sun Microsystems of Canada, Inc.