[ceph-users] New OSD with weight 0, rebalance still happen...

Janne Johansson icepic.dz at gmail.com
Fri Nov 23 03:48:18 PST 2018


Den fre 23 nov. 2018 kl 11:08 skrev Marco Gaiarin <gaio at sv.lnf.it>:

> Reading ceph docs lead to me that 'ceph osd reweight' and 'ceph osd crush
> reweight' was roughly the same, the first is effectively 'temporary'
> and expressed in percentage (0-1), while the second is 'permanent' and
> expressed, normally, as disk terabyte.
>
> You are saying that insted the first modify only the disk occupation,
> while only the latter alter the crush map.

The crush weight tells the cluster how much this disk adds to the
capacity of the host it is attached to,
the OSD weight says  (from 0 to 1) how much of the advertized size it
actually wants to receive/handle.
If you add crush weight, data will flow to the node, but if it has low
OSD weight, the other OSDs on the
host will have to bear the extra data. So starting out with 0 for
crush and 1.0 for OSD weight is fine, it
will not cause data movement, until you start (slowly perhaps) to add
to the crush weight until it matches
the size of the disk.

--
May the most significant bit of your life be positive.


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