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Questions about OSDs and HDDs

Good afternoon,

I am planning to implement petasan but I have several "groups" of different hard disks and I would like to be able to separate them, for example:

The idea is to set up 3 servers with:

4x NVME
4x SSD
4x HDD

I would like to be able to create separate groups to be able to close ISCSI units for each group, 1 for NVME, another for SSD and another for HDD.

Is this configuration possible?
How can I do this?

Thanks

You will need to create crush rules, then use the rules to create pools.  Have a look at the crush rules page, there are already crush rule templates for hdd and ssd .

By default when you add an OSD, the system will either detect it as hdd or ssd (for both nvime and sata ssd). You can add your own custom drive class (in addition to built-in hdd/ssd) in the add OSD page, for example for nvme or even specific model drives.  If you add custom class, you will need to create a crush rule to use that class (you can base it on existing hdd/ssd rules), then a pool using this rule to store on the classified drives.

As a side note, it is better to reserve 1  of your ssds to be a journal drive to your 4 hdds.