[lustre-discuss] question about /proc/fs/lustre/osc/ and llapi functions.

[Dilger, Andreas]

On Apr 7, 2017, at 18:06, John Bauer <bauerj at iodoctors.com> wrote:
> 
> In /proc/fs/lustre/osc/ is an entry for every osc of all the lustre files systems on a client node of the form nbp9-OST0124-osc-ffff880ffaa4bc00
> 
> My I/O instrumentation library tracks OSC's associated with an application file by reading the files in the directory for each OSC the application file is striped on.
> I am trying to avoid the use of opendir() and readdir() to find the OSC entry of interest as there are 1284 entries in the lustre/osc directory, and I do this for hundreds of application files on hundreds of ranks.
> I would like to generated the names of the osc entries I need, on the fly, given the discoverable file system name and osc indices.
> 
> I can find the file system name, nbp9, with llapi_getname().  I can generate the OSTxxxx part with the osc index from llapi_get_stripe().
> My question is, where do I find the ffff880ffaa4bc00 that is part of the directory entry for each OSC?  The value would appear to be file system
> related, as each OSC associated with a given file system has the same value.  OSC's of a different file system have a different value. Is there an llapi_xxxx() call that will get me this value.


There is llapi_getname() which will return the fsname and the instance identifier.

Cheers, Andreas
--
Andreas Dilger
Lustre Principal Architect
Intel Corporation