On 2016-10-18T11:36:42, Christian Balzer <ch...@gol.com> wrote:

> > Cache tiering in Ceph works for this use case. I assume you mean in
> > your UI?
> May well be, but Oliver suggested that cache-tiering is not supported with
> Hammer (0.94.x), which it most certainly is.

Right, we've got some success stories on Hammer already with it. Though
I much prefer Jewel too. ;-)

> > Though we all are waiting for Luminous to do away with the need for
> > cache tiering to do rbd to ec pools ...
> Well, there's the EC band-aid use case for cache-tiers, but they can be
> very helpful otherwise, depending on the size of working set/cache-pool,
> configuration of the cache-pool (write-back vs. read-forward) and
> specific use case.

Right. The main problem in my experience with cache tiering is that one
needs to know the answers to a bunch of questions most customers don't
have ;-) e.g., configuring the working set, flush/eviction policies,
etc. It's very helpful in some use cases, but mainly we're seeing it
used in the "band aid" mode. And I'd really love to get rid of those.


SUSE Linux GmbH, GF: Felix Imend├Ârffer, Jane Smithard, Graham Norton, HRB 21284 
(AG N├╝rnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde

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