[Lustre-discuss] Lustre & SQLite

Michal Wesolowski gmickyw at gmail.com
Thu Feb 12 00:43:38 PST 2009


Andreas Dilger wrote:
> 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. 
I saw this too, but my impression was that this remark apply to previous 
deliberations about buggy implementation of advisory locks on some NFS systems.

regards

michal



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