For future reference I found these 2 links which answer most of the questions:

We have about 250TB (x3) in our cluster so I am leaning toward not changing 
things at this point because it sounds like there will be a significant amount 
of data movement involved for not a lot in return.

If anyone knows of a strong reason I should change the tunables profile away 
from what I have…then please let me know so I don’t end up running the cluster 
in a sub-optimal state for no reason.


Shain Miley | Manager of Systems and Infrastructure, Digital Media | | 202.513.3649

From: ceph-users <> on behalf of Shain Miley 
Date: Monday, February 4, 2019 at 3:03 PM
To: "" <>
Subject: [ceph-users] crush map has straw_calc_version=0 and legacy tunables on 

I just upgraded our cluster to 12.2.11 and I have a few questions around 
straw_calc_version and tunables.

Currently ceph status shows the following:

crush map has straw_calc_version=0
crush map has legacy tunables (require argonaut, min is firefly)

  1.  Will setting tunables to optimal also change the staw_calc_version or do 
I need to set that separately?

  2.  Right now I have a set of rbd kernel clients connecting using kernel 
version 4.4.  The ‘ceph daemon sessions’ command shows that this client 
is still connecting using the hammer feature set (and a few others on jewel as 

"MonSession(client.113933130 is open allow *, 
features 0x7fddff8ee8cbffb (jewel))",  “MonSession(client.112250505 is open allow *, features 0x106b84a842a42 (hammer))",

My question is what is the minimum kernel version I would need to upgrade the 
4.4 kernel server to in order to get to jewel or luminous?

  1.  Will setting the tunables to optimal on luminous prevent jewel and hammer 
clients from connecting?  I want to make sure I don’t do anything will prevent 
my existing clients from connecting to the cluster.

Thanks in advance,

Shain Miley | Manager of Systems and Infrastructure, Digital Media | | 202.513.3649
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