Hi Luke, Am 10.09.21 um 13:27 schrieb Luke Hall:
I know that ceph recognises SSDs as distinct from HDDs from their physical device ids etc. In a setup with 50/50 HDDs/SSDs does ceph do anything natively to distinguish between the two speeds of storage? I.e do you need to create separate pools for fast/slow storage or is there something 'under the hood' which will manage which requests are sent to which type of storage?
There is nothing "under the hood" except the automatic detection of ssd versus hdd which is done by looking at /sys/block/sdX/queue/rotational.
It is best practice to have rulesets that select either hdd or ssd classes and then assign these rules to different pools.
It is not good practice to just mixed these classes in one pool, except for a transition period like with your project. The performance difference is just too large. Pools should have a uniform class of storage.
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