2 Dec
2019
2 Dec
'19
2:22 p.m.
You may be thinking of "lazytime". "relatime" only updates atime when
updating mtime, to prevent being inconsistent.
On Mon, Dec 2, 2019 at 4:46 AM Oliver Freyermuth
<freyermuth(a)physik.uni-bonn.de> wrote:
>
> Dear Cephers,
>
> we are currently mounting CephFS with relatime, using the FUSE client (version
13.2.6):
> ceph-fuse on /cephfs type fuse.ceph-fuse
(rw,relatime,user_id=0,group_id=0,allow_other)
>
> For the first time, I wanted to use atime to identify old unused data. My expectation
with "relatime" was that the access time stamp would be updated less often, for
example,
> only if the last file access was >24 hours ago. However, that does not seem to be
the case:
>
> ----------------------------------------------
> $ stat
/cephfs/grid/atlas/atlaslocalgroupdisk/rucio/group/phys-higgs/ed/cb/group.phys-higgs.17620861._000004.HSM_common.root
> ...
> Access: 2019-04-10 15:50:04.975959159 +0200
> Modify: 2019-04-10 15:50:05.651613843 +0200
> Change: 2019-04-10 15:50:06.141006962 +0200
> ...
> $ cat
/cephfs/grid/atlas/atlaslocalgroupdisk/rucio/group/phys-higgs/ed/cb/group.phys-higgs.17620861._000004.HSM_common.root
> /dev/null
> $ sync
> $ stat
/cephfs/grid/atlas/atlaslocalgroupdisk/rucio/group/phys-higgs/ed/cb/group.phys-higgs.17620861._000004.HSM_common.root
> ...
> Access: 2019-04-10 15:50:04.975959159 +0200
> Modify: 2019-04-10 15:50:05.651613843 +0200
> Change: 2019-04-10 15:50:06.141006962 +0200
> ...
> ----------------------------------------------
>
> I also tried this via an nfs-ganesha mount, and via a ceph-fuse mount with admin
caps,
> but atime never changes.
> Is atime really never updated with CephFS, or is this configurable?
>
> Something as coarse as "update at maximum once per day only" would be
perfectly fine for the use case.
>
> Cheers,
> Oliver
>
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