Hi,
instead of exporting/importing single objects via rados export/import
I would use 'rados cppool <pool-name> <dest-pool>' although it does a
linear copy of each object, so I'm not sure if that's so much better...
So first create a new replicated pool, 'rados cppool old new', then
rename the original pool, and then rename the new pool to the original
name.
Do you know if the remaining header objects change a lot or are read
very frequently? This could cause some interruption as well, not sure
if there's a smoother way, though. You could monitor (or maybe you
already do) the pool stats for that pool:
watch ceph osd pool stats <pool>
The cache tier approach is not really applicable here, the cache tier
can't be an ec pool:
ceph osd tier add test-cold-pool test-ec --force-nonempty
Error ENOTSUP: tier pool 'test-ec' is an ec pool, which cannot be a tier
Maybe someone else has some more experience to share.
Regards,
Eugen
Zitat von Burkhard Linke <Burkhard.Linke@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx>:
Hi,
we recently expanded a ceph cluster with a second site and want to
distribute data accordingly. Two replicate should be present on one
site, one replicate on the other site.
This works well for replicated pools, but not for EC pool, e.g. the
RGW data pool. I've added a second (replicated) storage class to RGW
and moved most of the data to it via lifecycle operations. Now about
670 GB are left in the EC pool, mostly the head objects which cannot
be moved.
I'm looking for the best method to migrate the existing EC pool to a
replicated pool, keeping the downtime a small as possible. So far
two methods seem to be feasible:
1. Cache tiering
Setup cache tiering with the EC pool as frontend pool and a
replicated target pool as backend pool. Set cache mode to proxy and
evict all objects from the EC pool the replicated pool. This will
reduce the downtime to a minimum (stopping all RGW instances,
changes the pool name in the placement definition, restart
instance). But I'm not sure whether a EC pool can acts as frontend
pool at all. And cache tiering is deprecated, so there might be
other downfalls.
2. Export / Import
Stop all RGW instances, export the EC pool's content with "rados
export", and import it into the target pool. This should be a safe
method, but will require a significant longer downtime (probably 24+
hours).
Are there any other options? I also evaluated working bucket wise by
creating a second placement set, disable access to a bucket, move
all objects belonging to that bucket from one pool to the other
(identifiable via the bucket's marker), change the placement setting
of the bucket and reenable access. Unfortunately I've didn't found a
good method to temporarily disable bucket access.
Best regards,
Burkhard Linke
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