Hi everyone. I have some questions since I'm benchmarking some machines to install a ceph cluster for my personal needs.
1) is a write operation between a ceph client and an OSD synchronous or asynchronous ? As far as I know, the primary OSD notifies the client once all OSDs (primary + replication) have scheduled the IO (the IO is in Op queue). But I'm not sure at all with this statement and the documentation is not very explicit for this question. 2) What does the min_alloc_size and min_blob_size bluestore parameters exactly mean ? I was searching a good FIO parameters set to reproduce some Ceph workload, but I was not able to choose a good block size. So I wanted to know what's the block size used by bluestore to write objects on disk, and I found alloc_size and blob_size but I don't understand which one is the good one to pick. Thank you very much for your help. Best regards.
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