[Lustre-discuss] Lustre delete efficency

[Brock Palen]

On Jun 26, 2008, at 1:57 PM, Stew Paddaso wrote:
> We are considering using Lustre as our backend file platform. The
> specific application involves storing a high-volume of sequential data
> writes, with a moderate amount of reads (mostly sequencial, with some
> random seeks). Our concern is with reclaiming space. As the file
> system fills, we need to be able to quickly delete the oldest files.
>
> Does Lustre have an efficient file delete? I'm not expecting specific
> metrics (though they would be nice if available), just some general
> info about the Lustre delete process (Does it immediately reclaim the
> space, or do it 'lazily' in the background? etc, etc.).
>

I don't know specifics about if space reclaiming is 'lazy' or not.   
But from what I have seen compared to regular ext3  deleting large  
files on lustre was very fast.  I expect this to be because ldsikfs  
is extent based and regular ext3 is not.  If I am wrong on this  
someone please correct me I really would like to know this also.

For me deleting large number of files _feels_  very quick compared to  
our NFS bobcat from onstor also. Even a operation like the following  
was much quicker (I wish there was a better way to do this)

du -h --max-depth=1

> Thanks.
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