Thanks Ilya for this clear explanation! I'm searching that for a long time Best practices is to have pg = pgp in order to "avoid" using of the same set of osd right ? (On a small cluster you will have) Sent from my iPhone > On 21 mai 2015, at 07:49, Ilya Dryomov <idryomov@xxxxxxxxx> wrote: > >> On Thu, May 21, 2015 at 12:12 PM, baijiaruo@xxxxxxx <baijiaruo@xxxxxxx> wrote: >> Re: what's the difference between pg and pgp? > > pg-num is the number of PGs, pgp-num is the number of PGs that will be > considered for placement, i.e. it's the pgp-num value that is used by > CRUSH, not pg-num. For example, consider pg-num = 1024 and pgp-num > = 1. In that case you will see 1024 PGs but all of those PGs will map > to the same set of OSDs. > > When you increase pg-num you are splitting PGs, when you increase > pgp-num you are moving them, i.e. changing sets of OSDs they map to. > > Thanks, > > Ilya > _______________________________________________ > ceph-users mailing list > ceph-users@xxxxxxxxxxxxxx > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com _______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
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