Thanks for getting back with a helpful reply. Assuming that I change the
source code to do custom placement, what are the places I need to look in
the code to do that? I am currently trying to change the CRUSH code, but is
there any place else I need to be concerned about?

Regards,
Shayan Saeed


On Mon, Jun 23, 2014 at 2:14 PM, Gregory Farnum <[email protected]> wrote:

> On Fri, Jun 20, 2014 at 4:23 PM, Shayan Saeed <[email protected]>
> wrote:
> > Is it allowed for crush maps to have multiple hierarchies for different
> > pools. So for example, I want one pool to treat my cluster as flat with
> > every host being equal but the other pool to have a more hierarchical
> idea
> > as hosts->racks->root?
>
> Yes. It can get complicated, so make sure you know exactly what you're
> doing, but you can create different "root" buckets and link the OSDs
> in to each root in different ways.
>
> >
> > Also, is it currently possible in ceph to have a custom placement of
> erasure
> > coded chunks. So for example within a pool, I want objects to reside
> exactly
> > on the OSDs I choose instead of doing placement for load balancing. Can I
> > specify something like: "For object 1, I want systematic chunks on rack1
> and
> > non systematic distributed between rack2 and rack3 and then for object
> 2, I
> > want systematic ones on rack2 and non systematic distributed between
> rack1
> > and rack3"?
>
> Not generally, no — you need to let the CRUSH algorithm place them.
> You can do things like specify specific buckets within a CRUSH rule,
> but that applies on a pool level.
> -Greg
> Software Engineer #42 @ http://inktank.com | http://ceph.com
>
> >
> > I would greatly appreciate any suggestions I get.
> >
> > Regards,
> > Shayan Saeed
> >
> > _______________________________________________
> > ceph-users mailing list
> > [email protected]
> > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
> >
>
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