Yes correct, hosts have indeed both ssd's and hdd's combined. Is this
not more of a bug then? I would assume the goal of using device classes
is that you separate these and one does not affect the other, even the
host weight of the ssd and hdd class are already available. The
algorithm should just use that instead of the weight of the whole host.
Or is there some specific use case, where these classes combined is
required?
-----Original Message-----
Cc: ceph-users
Subject: *****SPAM***** Re: [ceph-users] Re: hdd pg's migrating when
converting ssd class osd's
They're still in the same root (default) and each host is member of both
device-classes, I guess you have a mixed setup (hosts c01/c02 have both
HDDs and SSDs)? I don't think this separation is enough to avoid
remapping even if a different device-class is affected (your report
confirms that).
Dividing the crush tree into different subtrees might help here but I'm
not sure if that's really something you need. You might also just deal
with the remapping as long as it doesn't happen too often, I guess. On
the other hand, if your setup won't change (except adding more OSDs) you
might as well think about a different crush tree. It really depends on
your actual requirements.
We created two different subtrees when we got new hardware and it helped
us a lot moving the data only once to the new hardware avoiding multiple
remappings, now the older hardware is our EC environment except for some
SSDs on those old hosts that had to stay in the main subtree. So our
setup is also very individual but it works quite nice.
:-)
Zitat von :
> I have practically a default setup. If I do a 'ceph osd crush tree
> --show-shadow' I have a listing like this[1]. I would assume from the
> hosts being listed within the default~ssd and default~hdd, they are
> separate (enough)?
>
>
> [1]
> root default~ssd
> host c01~ssd
> ..
> ..
> host c02~ssd
> ..
> root default~hdd
> host c01~hdd
> ..
> host c02~hdd
> ..
> root default
>
>
>
>
> -----Original Message-----
> To: ceph-users@ceph.io
> Subject: [ceph-users] Re: hdd pg's migrating when converting ssd class
> osd's
>
> Are all the OSDs in the same crush root? I would think that since the
> crush weight of hosts change as soon as OSDs are out it impacts the
> whole crush tree. If you separate the SSDs from the HDDs logically
(e.g.
> different bucket type in the crush tree) the ramapping wouldn't affect
> the HDDs.
>
>
>
>
>> I have been converting ssd's osd's to dmcrypt, and I have noticed
>> that
>
>> pg's of pools are migrated that should be (and are?) on hdd class.
>>
>> On a healthy ok cluster I am getting, when I set the crush reweight
>> to
>
>> 0.0 of a ssd osd this:
>>
>> 17.35 10415 0 0 9907 0
>> 36001743890 0 0 3045 3045
>> active+remapped+backfilling 2020-09-27 12:55:49.093054
>> active+remapped+83758'20725398
>> 83758:100379720 [8,14,23] 8 [3,14,23] 3
>> 83636'20718129 2020-09-27 00:58:07.098096 83300'20689151 2020-09-24
>> 21:42:07.385360 0
>>
>> However osds 3,14,23,8 are all hdd osd's
>>
>> Since this is a cluster from Kraken/Luminous, I am not sure if the
>> device class of the replicated_ruleset[1] was set when the pool 17
>> was
>
>> created.
>> Weird thing is that all pg's of this pool seem to be on hdd osd[2]
>>
>> Q. How can I display the definition of 'crush_rule 0' at the time of
>> the pool creation? (To be sure it had already this device class hdd
>> configured)
>>
>>
>>
>> [1]
>> [@~]# ceph osd pool ls detail | grep 'pool 17'
>> pool 17 'rbd' replicated size 3 min_size 2 crush_rule 0 object_hash
>> rjenkins pg_num 64 pgp_num 64 autoscale_mode warn last_change 83712
>> flags hashpspool,selfmanaged_snaps stripe_width 0 application rbd
>>
>>
>> [@~]# ceph osd crush rule dump replicated_ruleset {
>> "rule_id": 0,
>> "rule_name": "replicated_ruleset",
>> "ruleset": 0,
>> "type": 1,
>> "min_size": 1,
>> "max_size": 10,
>> "steps": [
>> {
>> "op": "take",
>> "item": -10,
>> "item_name": "default~hdd"
>> },
>> {
>> "op": "chooseleaf_firstn",
>> "num": 0,
>> "type": "host"
>> },
>> {
>> "op": "emit"
>> }
>> ]
>> }
>>
>> [2]
>> [@~]# for osd in `ceph pg dump pgs| grep '^17' | awk '{print $17"
> "$19}'
>> | grep -oE '[0-9]{1,2}'| sort -u -n`; do ceph osd crush
>> | get-device-class
>> osd.$osd ; done | sort -u
>> dumped pgs
>> hdd
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