Ceph Crush map question

[brucexx]

I had a need at some point to create a secondary HDD pool on our ceph cluster, I added two rules:

ceph osd crush rule create-replicated replicated_rule_ssd default host ssd - for SSDs
ceph osd crush rule create-replicated replicated_rule_hdd default host hdd - for HDD

# rules
rule replicated_rule {
    id 0
    type replicated
    step take default
    step chooseleaf firstn 0 type host
    step emit
}
rule replicated_rule_ssd {
    id 1
    type replicated
    step take default class ssd
    step chooseleaf firstn 0 type host
    step emit
}
rule replicated_rule_hdd {
    id 2
    type replicated
    step take default class hdd
    step chooseleaf firstn 0 type host
    step emit
}

This was just temporary, now I am going full ssd. Should I remove that HDD replicated rule or it does not matter , also is it best practice to create a replicated rule for the ssd class or use the default rule ? The goal is to have only the same SSDs in that cluster.

Thank you

 

[gurubert]

Just the rule does not matter if there is no pool using the rule.

You could re-configure all your pools to use the first rule "replicated_rule" when you only have the same type of SSDs in the cluster, but it may cause some backfilling traffic. After that you could remove both rules that reference the device classes.