* Questions about PG ID to OSDs
@ 2011-02-21 9:05 Jeff Wu
2011-02-21 20:30 ` Sage Weil
0 siblings, 1 reply; 2+ messages in thread
From: Jeff Wu @ 2011-02-21 9:05 UTC (permalink / raw)
To: ceph-devel; +Cc: Sage Weil
Hi ,
I'm reading CRUSH and RADOS thesis,from these thesis ,
i can get the algorithms:
object_id = <object_number,inode_number>;
pg_id = (r,hash(object_id) & mask) ; // closely resembles consistent
hashing
but i am wondering how to map a pg_id to OSDs by CRUSH .
Example ,
if pg_id = 1.12,exist osd0,osd1,osd2,osd3,
then how to map pg_id = 1.12 to these osds ? the algorithms ? the
detail steps ?
Thanks a lot.
Jeff .C.P.Wu
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: Questions about PG ID to OSDs
2011-02-21 9:05 Questions about PG ID to OSDs Jeff Wu
@ 2011-02-21 20:30 ` Sage Weil
0 siblings, 0 replies; 2+ messages in thread
From: Sage Weil @ 2011-02-21 20:30 UTC (permalink / raw)
To: Jeff Wu; +Cc: ceph-devel
On Mon, 21 Feb 2011, Jeff Wu wrote:
> I'm reading CRUSH and RADOS thesis,from these thesis ,
> i can get the algorithms:
>
> object_id = <object_number,inode_number>;
> pg_id = (r,hash(object_id) & mask) ; // closely resembles consistent
> hashing
>
> but i am wondering how to map a pg_id to OSDs by CRUSH .
> Example ,
> if pg_id = 1.12,exist osd0,osd1,osd2,osd3,
> then how to map pg_id = 1.12 to these osds ? the algorithms ? the
> detail steps ?
The CRUSH algorithm is described in detail by
http://ceph.newdream.net/papers/weil-crush-sc06.pdf
sage
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2011-02-21 20:30 ` Sage Weil
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