Future: Filesystem ACL and SCM

Matthew Galgoci mgalgoci at redhat.com
Tue Mar 20 20:06:16 UTC 2007

> I talked with a few filesystem experts within Red Hat.  They said...
> - ext3 has a limit of 4KB for xattr data.  If you use the standard encoding of
> 8 bytes per uid, that has a limit of roughly 100 entities that could be
> associated with a file.  Is this too limiting?  I dunno. Perhaps it need not
> be too limiting if more extensive use of group-based-ACL's are used.
> - XFS could possibly allow a maximum of 64KB xattr's per file, but that is
> very inefficient in filesystem storage.
> - xattr's are currently not supported by NFS.

The other thing to concider is backup and restore of acls and xattrs. I think
this area is probably a weak spot as well but I believe star and rsync do
have some kind of support for acls.

Matthew Galgoci
GIS Production Operations
Red Hat, Inc
919.754.3700 x44155

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