[Lustre-discuss] Questions about Lustre ACLs
Kilian CAVALOTTI
kilian at stanford.edu
Fri Jul 25 16:56:38 PDT 2008
Hi all,
I've got a couple questions about ACLs in Lustre:
1. When they're enabled on the MDS, can a client mount the filesystem
without them? It doesn't seem to be the case, but at the same time, the
mount.lustre manpage mentions the noacl option in the "client-specific"
section.
See, for instance:
Checking ACLs on the MDS:
# lctl get_param -n mdc.home-MDT0000-mdc-*.connect_flags | grep acl
acl
Mounting the client with no ACLs
# mount -t lustre -o noacl ibmds2 at o2ib:/home /home
ACLs are still in use:
# strace ls -al /home/kilian/mpihw.c 2>&1 | grep xattr
getxattr("/home/kilian/mpihw.c", "system.posix_acl_access"..., 0x0, 0)
= -1 ENODATA (No data available)
getxattr("/home/kilian/mpihw.c", "system.posix_acl_default"..., 0x0, 0)
= -1 ENODATA (No data available)
I believe getxattr() should return EOPNOTSUPP instead of ENODATA, if
ACLs were disabled.
2. My second question is about the overhead induced by the ACLs. I
didn't do any quantifying measurements, but having ACLs enabled seems
to slower all MDS operations. A "ls" in a directory containing a lot of
files "feels" way slower when ACLs are enabled on the MDS. Is that
something to be expected?
Thanks,
--
Kilian
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