Hi,
On 12/17/20 8:57 PM, Patrick Donnelly wrote:
On Thu, Dec 17, 2020 at 11:35 AM Stefan Kooman <stefan@xxxxxx> wrote:
On 12/17/20 7:45 PM, Patrick Donnelly wrote:
When a file system is newly created, it's assumed you want all the
stable features on, including multiple MDS, directory fragmentation,
snapshots, etc. That's what those flags are for. If you've been
upgrading your cluster, you need to turn those on yourself.
OK, fair enough. So I tried adding "allow_dirfrags" which gives me:
ceph fs set cephfs allow_dirfrags true
Directory fragmentation is now permanently enabled. This command is
DEPRECATED and will be REMOVED from future releases.
And I enabled snapshot support:
ceph fs set cephfs allow_new_snaps true
enabled new snapshots
However, this has not changed the "flags" of the filesystem in any way.
So I guess there are still features not enabled that are enabled on
newly installed clusters. Where can I find a list of features that I can
enable?
Apologies for linking code:
https://github.com/ceph/ceph/blob/master/src/include/ceph_fs.h#L275-L285
No problem.
I have searched through documentation but I don't see anything
related. It's also not described / suggested in the part about upgrading
the MDS cluster (IMHO that would be a logical place) [1].
You're the first person I'm aware of asking for this. :)
Somehow I'm not suprised :-). But on the other hand, I am. I will try to
explain this. Maybe this works best with an example.
Nautilus 14.2.4 cluster here (upgraded from luminous, mimic).
relevant part of ceph -s:
mds: cephfs:1 {0=mds2=up:active} 1 up:standby-replay
^^ Two MDSes in this cluster: one active and one standby-replay.
ceph fs get cephfs |grep flags
flags 1e
Let's try to enable standby replay support:
ceph fs set cephfs allow_standby_replay true
That worked, did flags change?
ceph fs get cephfs |grep flags
flags 3e
Yes! But why? I would expect the support for standby replay to have been
enabled already. How else would it work even without setting this fs
feature. But apparently it does, and does not need this feature to be
enabled like this. And that might explain that nobody ever wondered how
to change "ceph fs flags" in the first place. Is that correct?
At this point I ask myself the question: who / what uses the cephfs
flags, and what fort. Do I, as a storage admin, need to care about this
at all?
But hey, here we are, and now I would like to understand it.
If, just for the sake of upgrading clusters to have identical features,
I would like to "upgrade" the cephfs to support all ceph fs features, I
seem not to be able to do that:
ceph fs set cephfs
Invalid command: missing required parameter
var(max_mds|max_file_size|allow_new_snaps|inline_data|cluster_down|allow_dirfrags|balancer|standby_count_wanted|session_timeout|session_autoclose|allow_standby_replay|down|joinable|min_compat_client)
fs set <fs_name>
max_mds|max_file_size|allow_new_snaps|inline_data|cluster_down|allow_dirfrags|balancer|standby_count_wanted|session_timeout|session_autoclose|allow_standby_replay|down|joinable|min_compat_client
<val> {--yes-i-really-mean-it} : set fs parameter <var> to <val>
Error EINVAL: invalid command
I can choose between these:
max_mds|max_file_size|allow_new_snaps|inline_data|cluster_down|allow_dirfrags|balancer|standby_count_wanted|session_timeout|session_autoclose|allow_standby_replay|down|joinable|min_compat_client
Most of them I would not like to set at all (i.e down, joinable,
max_mds) as they are not "features" but merely a way to set the ceph fs
in a certain STATE.
So my question is: what do I need to enable to get an upgraded fs to get
say "flags 12" (Nautilus with snapshot support enabled AFAIK). Is that
at all possible?
The reason why I started this whole thread was to eliminate any Ceph
config related difference between production and test. But maybe I
should ask a different question: Does a (ceph-fuse / kernel) client use
the *cephfs flags* bit at all? If not than we don't have to focus on
this, and we can conclude we cannot reproduce the issue on our test
environment.
I hope above makes sense to you ;-).
Thanks,
Gr. Stefan
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