On Wed, Oct 2, 2019 at 10:56 PM Robert LeBlanc <robert@leblancnet.us> wrote:
Is there a way to have leveldb compact more frequently or cause it to come up for air more frequently and respond to heartbeats and process some IO?
you can manually trigger a compaction via the admin socket (or was it via ceph tell?) with the compact command, but I don't think that this helps with your workload.
I thought splitting PGs would help, but we are still seeing the problem (previously ~20 PGs per OSD to now ~150). I still have some space on the SSDs that I can double, almost triple the journal, but not sure if that will help in this situation.
no, a larger journal will not help for leveldb workloads. Big difference between FileStore journals and BlueStore DB devices: BlueStore actually puts all the metadata onto the SSD permanently, a FileStore journal is just a journal (and 5 GB is large enough, it won't use that much space for small operations like deletions). (The answer that you don't want to hear is probably the best way forward: upgrade to BlueStore) Paul
The other issue I'm seeing is that some IO just gets stuck when the OSDs are getting marked down and coming back through the cluster.
Thanks, Robert LeBlanc
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