Hi Jim, when you do reweighting, balancing will be triggered, how did you set 
it back? Setting back immediately or waiting for balancing to complete? I did 
try both on my cluster and couldn't see osd bench changed significantly like 
yours (actually no changes), however, my cluster is 12.2.12, not sure if that 
is the reason.



Moreover, I really can't figure out why flipping the reweight can make such 
difference. Hope experts can explain that.





------------------ Original ------------------
From: &nbsp;"Jim Forde";<[email protected]&gt;;
Date: &nbsp;Aug 7, 2020
To: &nbsp;"ceph-users"<[email protected]&gt;; 

Subject: &nbsp;[ceph-users] Re: Nautilus slow using "ceph tell osd.* bench"



SOLUTION FOUND!
Reweight the osd to 0, then set it back to where it belongs.
ceph osd crush reweight osd.0 0.0

Original
ceph tell osd.0 bench -f plain
bench: wrote 1 GiB in blocks of 4 MiB in 4.03434 sec at 254 MiB/sec 63 IOPS

After reweight of osd.0
ceph tell osd.0 bench -f plain
bench: wrote 1 GiB in blocks of 4 MiB in 1.54555 sec at 663 MiB/sec 165 IOPS
ceph tell osd.1 bench -f plain
bench: wrote 1 GiB in blocks of 4 MiB in 3.54652 sec at 289 MiB/sec 72 IOPS

After reweight of osd.1
ceph tell osd.0 bench -f plain
bench: wrote 1 GiB in blocks of 4 MiB in 0.948457 sec at 1.1 GiB/sec 269 IOPS
ceph tell osd.1 bench -f plain
bench: wrote 1 GiB in blocks of 4 MiB in 0.949384 sec at 1.1 GiB/sec 269 IOPS
ceph tell osd.2 bench -f plain
bench: wrote 1 GiB in blocks of 4 MiB in 3.56726 sec at 287 MiB/sec 71 IOPS

I have finished reweight proceedure on osd node 1 and all 6 osd's are back 
where they belong, but have 4 more nodes to go. Looks like this should fix it. 
If anyone has an alternative method for getting around this I am all ears.

Dave, would be interested to hear if this works for you.

-Jim
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