> Hi,
>
> I am thinking how to make ceph with 2 pools - fast and slow.
> Plan is to use SSDs and SATAs(or SAS) in the same hosts and define pools that
> use fast and slow disks accordingly. Later it would be easy to grow either pool
> by need.
>
> I found example for CRUSH map that does similar thing by defining 2 root
> hierarchies where hosts are used in steps
> http://ceph.com/docs/master/rados/operations/crush-map/ (see "Placing
> Different Pools on Different OSDS")
>
> but if 2 types of disks are in same hosts it will not work.
>
> How to do this? Do I have to define some fake entity in crushmap to make 2
> pools work on same hardware?
If I'm reading the documentation correctly, you probably have to run two (software) clusters. Ceph is capable of running multiple clusters on the same hardware.
http://ceph.com/docs/master/rados/configuration/ceph-conf/#running-multiple-clusters
You definitely don't need to create two clusters. You will need to create two parallel hierarchies in the CRUSH map, though -- one for "fast" and one for "slow". Just incorporate the proper disks in each.
-Greg
--
Software Engineer #42 @ http://inktank.com | http://ceph.com
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