Hi Adrian,
Is there a strict reason why you *must* upgrade the tunables?
It is normally OK to run with old (e.g. hammer) tunables on a luminous
cluster. The crush placement won't be state of the art, but that's not
a huge problem.
We have a lot of data in a jewel cluster with hammer tunables. We'll
upgrade that to luminous soon, but don't plan to set chooseleaf_stable
until there's less disruptive procedure, e.g. [1].
Cheers, Dan
[1] One idea I had to make this much less disruptive would be to
script something that uses upmap's to lock all PGs into their current
placement, then set chooseleaf_stable, then gradually remove the
upmap's. There are some details to work out, and it requires all
clients to be running luminous, but I think something like this could
help...
On Mon, May 14, 2018 at 9:01 AM, Adrian <aussieade@xxxxxxxxx> wrote:
> Hi all,
>
> We recently upgraded our old ceph cluster to jewel (5xmon, 21xstorage hosts
> with 9x6tb filestore osds and 3xssd's with 3 journals on each) - mostly used
> for openstack compute/cinder.
>
> In order to get there we had to go with chooseleaf_vary_r = 4 in order to
> minimize client impact and save time. We now need to get to luminous (on a
> deadline and time is limited).
>
> Current tunables are:
> {
> "choose_local_tries": 0,
> "choose_local_fallback_tries": 0,
> "choose_total_tries": 50,
> "chooseleaf_descend_once": 1,
> "chooseleaf_vary_r": 4,
> "chooseleaf_stable": 0,
> "straw_calc_version": 1,
> "allowed_bucket_algs": 22,
> "profile": "unknown",
> "optimal_tunables": 0,
> "legacy_tunables": 0,
> "minimum_required_version": "firefly",
> "require_feature_tunables": 1,
> "require_feature_tunables2": 1,
> "has_v2_rules": 0,
> "require_feature_tunables3": 1,
> "has_v3_rules": 0,
> "has_v4_buckets": 0,
> "require_feature_tunables5": 0,
> "has_v5_rules": 0
> }
>
> Setting chooseleaf_stable to 1, the crush compare tool says:
> Replacing the crushmap specified with --origin with the crushmap
> specified with --destination will move 8774 PGs (59.08417508417509% of the
> total)
> from one item to another.
>
> Current tunings we have in ceph.conf are:
> #THROTTLING CEPH
> osd_max_backfills = 1
> osd_recovery_max_active = 1
> osd_recovery_op_priority = 1
> osd_client_op_priority = 63
>
> #PERFORMANCE TUNING
> osd_op_threads = 6
> filestore_op_threads = 10
> filestore_max_sync_interval = 30
>
> I was wondering if anyone has any advice as to anything else we can do
> balancing client impact and speed of recovery or war stories of other things
> to consider.
>
> I'm also wondering about the interplay between chooseleaf_vary_r and
> chooseleaf_stable.
> Are we better with
> 1) sticking with choosleaf_vary_r = 4, setting chooseleaf_stable =1,
> upgrading and then setting chooseleaf_vary_r incrementally to 1 when more
> time is available
> or
> 2) setting chooseleaf_vary_r incrementally first, then chooseleaf_stable and
> finally upgrade
>
> All this bearing in mind we'd like to keep the time it takes us to get to
> luminous as short as possible ;-) (guestimating a 59% rebalance to take many
> days)
>
> Any advice/thoughts gratefully received.
>
> Regards,
> Adrian.
>
> --
> ---
> Adrian : aussieade@xxxxxxxxx
> If violence doesn't solve your problem, you're not using enough of it.
>
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>
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