On Wed, Mar 7, 2018 at 2:29 PM, John Spray <jspray@xxxxxxxxxx> wrote:
> On Wed, Mar 7, 2018 at 10:11 AM, Dan van der Ster <dan@xxxxxxxxxxxxxx> wrote:
>> Hi all,
>>
>> What is the purpose of
>>
>> ceph mds set max_mds <int>
>>
>> ?
>>
>> We just used that by mistake on a cephfs cluster when attempting to
>> decrease from 2 to 1 active mds's.
>>
>> The correct command to do this is of course
>>
>> ceph fs set <fsname> max_mds <int>
>>
>> So, is `ceph mds set max_mds` useful for something? If not, should it
>> be removed from the CLI?
>
> It's the legacy version of the command from before we had multiple
> filesystems. Those commands are marked as obsolete internally so that
> they're not included in the --help output,
Ahhh! It is indeed omitted from --help but I hadn't noticed because it
is still rather helpful if you go ahead and run the command:
# ceph mds set
Invalid command: missing required parameter
var(max_mds|max_file_size|allow_new_snaps|inline_data|allow_multimds|allow_dirfrags)
mds set max_mds|max_file_size|allow_new_snaps|inline_data|allow_multimds|allow_dirfrags
<val> {<confirm>} : set mds parameter <var> to <val>
Error EINVAL: invalid command
I suppose we just need a new generation of operators that would never
even try these old deprecated commands ;)
> but they're still handled
> (applied to the "default" filesystem) if called.
Hmm... does it apply if we never set the default fs (though only have one) ?
(How do we even see/get the default fs?)
What happened in our case is that I did `ceph mds set max_mds 1` then
deactivated rank 2. This caused some sort of outage which deadlocked
the mds's (they recovered after restarting). I assume the outage
happened because I deactivated rank 2 while we still had max_mds=2 at
the fs scope (and we had no standbys -- due to the v12.2.2->4 upgrade
breakage).
Thanks John!
Dan
>
> The multi-fs stuff went in for Jewel, so maybe we should think about
> removing the old commands in Mimic: any thoughts Patrick?
>
> John
>
>>
>> Cheers, Dan
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