Crush map configuration not persistant

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Bruggefan

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Feb 13, 2024
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Dear all

Yesterday I was installing a new ceph cluster in proxmox with 3 nodes.
Doing this I wanted to seperate the SSD disks from HDD disks.

- Therefor I created 2 new roots (1 for SSD OSD's, 1for HDD OSD's) with 3 nodes in every root.

- I added my SSD OSD's to the appropriate root and created a pool of SSD storage targetting those buckets with the appropriate crush rules.

- Did the same with all HDD disks


afterwards ceph osd crush tree showed me perfectly my configuration, as did the GUI.
I installed some VM's on it with windows server and pfsense and all went well.

As this cluster is still being configured and I was planning to put it in production tomorrow, I shut all VM's and shutdown all nodes of the cluster.
(yeah I try to do some powersavings as well ;) )
Today I started all nodes again and I wanted to proceed my configurations, but I saw my VM's wouldn't start.
In the and I can see all my OSD's are back in default root and therefor I get troubles with my pools ofcourse...


you can see my current crush tree here:1707834750542.png
OSD.0 should be in node1-ssd, osd.1 in node2-ssd,...
OSD.3 & .4 should be in node1-hdd, OSD.4 & .6 should be in node2-hdd,...

Can someone help me out why my config of my OSD's got lost and how to prevent it in the future?
how I can save the progress I made?

Thanks in advance!
 
I dont know why it happend but im not sure, if pve ceph does allow multiple "roots"? in your case just use the defaults, use device classes in the osd-creation (via web-ui) but make sure you create a custom crushrule that applies to the devices used. After that, create pools and asign the correct crush-rule. This post will help you out:

https://forum.proxmox.com/threads/ceph-classes-rules-and-pools.60013/
 
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Thank you for your answers.

I did try to use it the way you both mentioned. The result of this approach was a SSD-pool of approximately 1TB and a HDD pool of also approximately 1TB.
Which was obviously not what I was trying to accomplish. Hence you know why I was googling around and came to the solution I have now...
If Proxmox is overriding settings, it is probably possible to change a config-file to make this a permanent configuration?

Thanks in advance!
 
Bruggefan said:
Thank you for your answers.

I did try to use it the way you both mentioned. The result of this approach was a SSD-pool of approximately 1TB and a HDD pool of also approximately 1TB.
Which was obviously not what I was trying to accomplish. Hence you know why I was googling around and came to the solution I have now...
If Proxmox is overriding settings, it is probably possible to change a config-file to make this a permanent configuration?

Thanks in advance!
Click to expand...
Im not sure what you actually did but I can confirm that the way I posted is absolutely correct, and also the fact that you only have 1TB SSD then. How do you get to the assumption it should NOT be 1TB? You only have 1 ssd per host which is 1TB, Ceph uses 3way replica. So you can only use a third of the sum of all the disks you have in a device-class (like ssd).

So whatever you have configured Im sure, theres no official (Proxmox) way to make this permanent and Im 99% sure that your setup has some big flaws which might cause trouble in the future.
 
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