[gpfsug-discuss] Metadata only system pool

[Chris Hoffman]

If you are still running out of space when mmdf shows preallocated inodes left I'd check MaxInodes vs AllocInodes for that fileset.


You can run:

mmlsfileset <fs> -L


Thanks,

Chris?




________________________________
From: gpfsug-discuss-bounces at spectrumscale.org <gpfsug-discuss-bounces at spectrumscale.org> on behalf of Frederick Stock <stockf at us.ibm.com>
Sent: Tuesday, January 23, 2018 9:25 AM
To: gpfsug main discussion list
Subject: Re: [gpfsug-discuss] Metadata only system pool

One possibility is the creation/expansion of directories or allocation of indirect blocks for large files.

Not sure if this is the issue here but at one time inode allocation was considered slow and so folks may have pre-allocated inodes to avoid that overhead during file creation.  To my understanding inode creation time is not so slow that users need to pre-allocate inodes.  Yes, there are likely some applications where pre-allocating may be necessary but I expect they would be the exception.  I mention this because you have a lot of free inodes and of course once they are allocated they cannot be de-allocated.

Fred
__________________________________________________
Fred Stock | IBM Pittsburgh Lab | 720-430-8821
stockf at us.ibm.com



From:        "Buterbaugh, Kevin L" <Kevin.Buterbaugh at Vanderbilt.Edu>
To:        gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:        01/23/2018 12:17 PM
Subject:        [gpfsug-discuss] Metadata only system pool
Sent by:        gpfsug-discuss-bounces at spectrumscale.org
________________________________



Hi All,

I was under the (possibly false) impression that if you have a filesystem where the system pool contains metadata only then the only thing that would cause the amount of free space in that pool to change is the creation of more inodes ... is that correct?  In other words, given that I have a filesystem with 130 million free (but allocated) inodes:

Inode Information
-----------------
Number of used inodes:       218635454
Number of free inodes:       131364674
Number of allocated inodes:  350000128
Maximum number of inodes:    350000128

I would not expect that a user creating a few hundred or thousands of files could cause a "no space left on device" error (which I've got one user getting).  There's plenty of free data space, BTW.

Now my system pool is almost "full":

(pool total)           2.878T                                   34M (  0%)        140.9M ( 0%)

But again, what - outside of me creating more inodes - would cause that to change??

Thanks...

Kevin

-
Kevin Buterbaugh - Senior System Administrator
Vanderbilt University - Advanced Computing Center for Research and Education
Kevin.Buterbaugh at vanderbilt.edu<mailto:Kevin.Buterbaugh at vanderbilt.edu>- (615)875-9633


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