From: Sage Weil Date: Tue, 13 Nov 2012 22:34:53 +0000 (-0800) Subject: doc: update crush weight ramping process X-Git-Tag: v0.55~105 X-Git-Url: http://git-server-git.apps.pok.os.sepia.ceph.com/?a=commitdiff_plain;h=0d42e9762b78783357fcbaedbf2641f83ece1745;p=ceph.git doc: update crush weight ramping process Signed-off-by: Sage Weil --- diff --git a/doc/cluster-ops/add-or-rm-osds.rst b/doc/cluster-ops/add-or-rm-osds.rst index ec24315ea54c..ea891472f1c6 100644 --- a/doc/cluster-ops/add-or-rm-osds.rst +++ b/doc/cluster-ops/add-or-rm-osds.rst @@ -136,11 +136,33 @@ hard disks than older hosts in the cluster (i.e., they may have greater weight). .. topic:: Argonaut (v0.48) Best Practices - To limit impact on user I/O, add an OSD to the CRUSH map with an initial - weight of ``0``. Then, ramp up the CRUSH weight a little bit at a time - (e.g., ``0.2``) and allow migration to complete. Continue to increment - the CRUSH weight until you reach your desired CRUSH weight. This practice - will no longer be necessary in Bobtail and subsequent releases. + To limit impact on user I/O performance, add an OSD to the CRUSH map + with an initial weight of ``0``. Then, ramp up the CRUSH weight a + little bit at a time. For example, to ramp by increments of ``0.2``, + start with:: + + ceph osd crush reweight {osd-id} .2 + + and allow migration to complete before reweighting to ``0.4``, + ``0.6``, and so on until the desired CRUSH weight is reached. + + To limit the impact of OSD failures, you can set:: + + mon osd down out interval = 0 + + which prevents down OSDs from automatically being marked out, and then + ramp them down manually with:: + + ceph osd reweight {osd-num} .8 + + Again, wait for the cluster to finish migrating data, and then adjust + the weight further until you reach a weight of 0. Note that this + problem prevents the cluster to automatically re-replicate data after + a failure, so please ensure that sufficient monitoring is in place for + an administrator to intervene promptly. + + Note that this practice will no longer be necessary in Bobtail and + subsequent releases. Adding an OSD (Chef)