[Lustre-discuss] Lustre & SQLite

[Oleg Drokin]

Hello!

On Feb 12, 2009, at 3:29 PM, Michal Wesolowski wrote:
>> Yes, this is somewhat outdated.
>> 1.6.6 and above have posix advisory locking working (though  
>> performance is not ideal,
>> especially if you have many clients doing a lot of locks on the  
>> same file at the same
>> time).
> Do you mean file locking mechanism in Lustre doesn't perform as  
> efficiently as on local system or is not yet optimized? Or is there  
> any general impact on Lustre when at least one node has flock option  
> turned on? For example additional burden on MDS or OSSes which  
> results in lower IO/s performance.

It is both not very optimized and slower than local system since it  
needs to send network rpcs for locking (Except for the localflock  
which is same speed as for local fs).
The performance impact would only be realized if not only you mount  
with -o flock, but actually use posix locking, and mostly only in  
those operations.
There is no impact on OSS operations at all. The only MDS impact is  
there is now a bit more processing to handle those locking RPCs.

Bye,
     Oleg