[Lustre-discuss] Performance issues in directories after large number of I/O operations on small files.

[Brian J. Murrell]

On Wed, 2008-12-10 at 12:18 -0800, Sebastian Gutierrez wrote:
> Hello
> I have a user that keeps having issues after using a directory and
> performing quite a number of I/O operations on the folder.
> 
> If he moves delete creates files in a directory on his luster working
> directory the directory eventually gets unmanageably slow.  He is
> working with a large number of small files.
> Here is a example of a copied directory that shows the directory
> metadata much smaller but has the exact same data in it.
> 
> drwxr-sr-x  3 user group     4096 Dec  3 17:26 StatisticsQualScore
> drwxr-sr-x  3 user group 12623872 Dec  3 15:59 StatisticsQualScore_old
> 
> After a copy of the directory the directory speeds improve.
> 
> Is this happening because of a LRU sizing issue or could there be
> something else that could be causing this?

Yeah, this sounds like the LRU dynamic resizing bug, 17282.

> We currently have a work
> around but I would like to have a better understanding of this and
> possible solution or option I can implement.

The work-around is to set a static LRU size.  Details are in the bug.

b.

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