[gpfsug-discuss] Metadata space usage NFS4 vs POSIX ACL

[Marc A Kaplan]

2TB of extra meta data space for 100M files with ACLS?!  I think that would
be 20KB per file!  Does seem there's some mistake here.
Perhaps 2GB ? or 20GB?  I don't see how we get to 2TeraBytes!

ALSO, IIRC GPFS is supposed to use an ACL scheme where identical ACLs are
stored once and each file with the same ACL just has a pointer to that same
ACL.
So no matter how many files have a particular ACL, you only "pay" once...
An ACL is stored more compactly than its printed format, so I'd guess your
ordinary ACL with a few users and groups would be less than 200 bytes.



From:	Michal Zacek <m.zacek77 at gmail.com>


Hello,

we decided to convert NFS4 acl to POSIX (we need share same data
between  SMB, NFS and GPFS clients), so I created script to convert
NFS4 to posix ACL. It is very simple, first I do "chmod -R 770 DIR" and
then "setfacl -R ..... DIR".  I was surprised that conversion to posix
acl has taken more then 2TB of metadata space.There is about one hundred
million files at GPFS filesystem. Is this expected behavior?

Thanks,
Michal
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