[Lustre-discuss] query mds for 'stat' info

[Andreas Dilger]

On Sep 16, 2009  11:56 +0200, Isaac Hailperin wrote:
> I'd like to implement sliding window and hight water mark deletion on a 
> lustre filesystem. For that I need information from all files. A first 
> idea was to recursivly traverse the file tree and to a `stat filename` 
> for every file to collect the meta data.
> 
> Now since in lustre the meta data is stored on the mds, I though that 
> maybe there is a more efficient way of collecting the information.
> 
> So the question is: is there a way that I could query the mds for the 
> information that stat would give me(I need access, modify, creation time 
> plus the file size). And if so, can someone guess the performance 
> increase of quering the mds directly over using `stat` ?

This is what e2scan is for, in the Lustre e2fsprogs.

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