On 2016-04-02T07:54:05, Wido den Hollander <wido@xxxxxxxx> wrote:
>
> > Op 1 april 2016 om 17:36 schreef Sage Weil <sweil@xxxxxxxxxx>:
> >
> >
> > Hi all,
> >
> > There are a couple of looming features for ceph-disk:
> >
> > 1- Support for additional devices when using BlueStore. There can be up
> > to three: the main device, a WAL/journal device (small, ~128MB, ideally
> > NVRAM), and a fast metadata device (as big as you have available; will be
> > used for internal metadata).
> >
> > 2- Support for setting up dm-cache, bcache, and/or FlashCache underneath
> > filestore or bluestore.
> >
>
> Keep in mind that you can't create a partition on a bcache device. So when using
> bcache, the journal has to be filebased and not a partition.
Is there a point to running the journal on bcache? I see a point for
bcache for the (potentially on HDD) actual data store - but the
WAL/journal, would that not be directly on NVMe/PM/SSD (at the very
least)? Without an intervening cache?
Regards,
Lars
--
Architect SDS, Distinguished Engineer
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
"Experience is the name everyone gives to their mistakes." -- Oscar Wilde
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