If you successfully get every object into the cache tier and then flush it to the new pool, you've copied every object in your cluster twice. And
as you mentioned, you can't guarantee that the flush will do what you need. I don't have much experience with RGW, but would it work to write a loop through your objects (rados ls) to access them and copy them directly to the new pool using RGW? Of course
this will be problematic to getting everything if the cluster is allowed to receive writes during the copy, but if you can ensure that it would be read only during this time then it should work.
 |
David Turner |
Cloud Operations Engineer |
StorageCraft
Technology Corporation 380 Data Drive Suite 300 | Draper | Utah | 84020 Office: 801.871.2760 | Mobile: 385.224.2943 |
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________________________________________
From: ceph-users [ceph-users-bounces@xxxxxxxxxxxxxx] on behalf of Blair Bethwaite [blair.bethwaite@xxxxxxxxx]
Sent: Tuesday, February 07, 2017 8:32 AM
To: ceph-users@xxxxxxxxxxxxxx
Subject: Re: EC pool migrations
On 7 February 2017 at 23:50, Blair Bethwaite <blair.bethwaite@xxxxxxxxx> wrote:
> 1) insert a large enough temporary replicated pool as a cache tier
> 2) somehow force promotion of every object into the cache (don't see
> any way to do that other than actually read them - but at least some
> creative scripting could do that in parallel)
> 3) once #objects in cache = #objects in old backing pool
> then stop radosgw services
> 4) remove overlay and tier remove
> 6) now we should have identical or newer data in the temporary
> replicated pool and no caching relationship
> then add the temporary replicated pool as a tier (--force-nonempty) to
> the new EC pool
> 7) finally cache-flush-evict-all and remove the temporary replicated pool
That all seemed to work right up to the final step. flushing/evicting
of course doesn't guarantee the contents of the cache get written to
the backing pool. This must be because it's properties in the cache
that decide whether to forward anything down to the backing pool and
as these objects haven't been changed the cache just throws them
away... Is there a way around this?
--
Cheers,
~Blairo
_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
From: ceph-users [ceph-users-bounces@xxxxxxxxxxxxxx] on behalf of Blair Bethwaite [blair.bethwaite@xxxxxxxxx]
Sent: Tuesday, February 07, 2017 8:32 AM
To: ceph-users@xxxxxxxxxxxxxx
Subject: Re: EC pool migrations
On 7 February 2017 at 23:50, Blair Bethwaite <blair.bethwaite@xxxxxxxxx> wrote:
> 1) insert a large enough temporary replicated pool as a cache tier
> 2) somehow force promotion of every object into the cache (don't see
> any way to do that other than actually read them - but at least some
> creative scripting could do that in parallel)
> 3) once #objects in cache = #objects in old backing pool
> then stop radosgw services
> 4) remove overlay and tier remove
> 6) now we should have identical or newer data in the temporary
> replicated pool and no caching relationship
> then add the temporary replicated pool as a tier (--force-nonempty) to
> the new EC pool
> 7) finally cache-flush-evict-all and remove the temporary replicated pool
That all seemed to work right up to the final step. flushing/evicting
of course doesn't guarantee the contents of the cache get written to
the backing pool. This must be because it's properties in the cache
that decide whether to forward anything down to the backing pool and
as these objects haven't been changed the cache just throws them
away... Is there a way around this?
--
Cheers,
~Blairo
_______________________________________________
ceph-users mailing list
ceph-users@xxxxxxxxxxxxxx
http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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