Nautilus: Decommission an OSD Node

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]



I've recently made the decision to gradually decommission my Nautilus
cluster and migrate the hardware to a new Pacific or Quincy cluster. By
gradually, I mean that as I expand the new cluster I will move (copy/erase)
content from the old cluster to the new, making room to decommission more
nodes and move them over.

In order to do this I will, of course, need to remove OSD nodes by first
emptying the OSDs on each node.

I noticed that pgremapper (a version prior to October 2021) has a 'drain'
subcommand that allows one to control which target OSDs would receive the
PGs from the source OSD being drained.  This seemed like a good idea:  If
one simply marks an OSD 'out', it's contents would be rebalanced to other
OSDs on the same node that are still active, which seems like it would make
a lot of unnecessary data movement and also make removing the next OSD take

So I went through the trouble of creating a 'really long' pgremapper drain
command excluding the OSDs of two nodes as targets:

# bin/pgremapper drain 16 --target-osds
--allow-movement-across host  --max-source-backfills 75 --concurrency 20
--verbose --yes

However, when this is complete OSD 16 actually contains more PGs than
before I started.  It appears that the mapping generated by pgremapper also
back-filled the OSD as it was draining it.

So did I miss something here?  What is the best way to proceed?  I
understand that it would be mayhem to mark 8 of 72 OSDs out and then turn
backfill/rebalance/recover back on.  But it seems like there should be a
better way.




Dave Hall
Binghamton University
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx

[Index of Archives]     [Information on CEPH]     [Linux Filesystem Development]     [Ceph Development]     [Ceph Large]     [Ceph Dev]     [Linux USB Development]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [xfs]

  Powered by Linux