[lustre-discuss] find xdev?

Andreas Dilger adilger at whamcloud.com
Tue Sep 10 14:48:37 PDT 2019

On Sep 10, 2019, at 10:34, Michael Di Domenico <mdidomenico4 at gmail.com<mailto:mdidomenico4 at gmail.com>> wrote:

are there any plans to support -xdev to lfs find?

I don't think "lfs find -xdev" has never been a priority for Lustre, since it is rare for Lustre filesystems to be
mounted in a nested manner.  Since people already run multiple "lfs find" tasks in parallel on different
clients to get better performance, it isn't hard to run separate tasks from the top-level mountpoint of
different filesystems.  What is the use case for this?

You could file a feature request in Jira, but I don't think it would be a high priority vs. even some other
"lfs find" improvements (e.g. LSOM support, -nlink, -printf, -perm, MPI, etc) unless there was some
really important use case.  Of course, patches are also welcome.

along the same vein, can anyone state whether there's any actual
performance gain walking the filesystem using find vs lfs find?

For "find" vs. "lfs find" performance, this depends heavily on what the search parameters are.  If just
the filename, they will be the same.  If it includes some MDT-specific attributes (e.g. uid, gid) then
"lfs find" can be significantly faster (e.g 3-5x0.  If it is uses file size, then they will be about the same
unless there are other MDT-only parameters, or once LSOM support is landed (hopefully 2.13).

Cheers, Andreas
Andreas Dilger
Principal Lustre Architect

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