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0 pointspatrakov2y ago0 comments

It is important to specify which kind of latency percentile this is. Checking on a customer's cluster (made from 336 SATA SSDs in 15 servers, so not the best one in the world):

  50th percentile = 1.75 ms
  90th percentile = 3.15 ms
  99th percentile = 9.54 ms

That's with 700 MB/s of reads and 200 MB/s of writes, or approximately 7000 reads IOPS and 9000 writes IOPS.

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louwrentius2y ago

These numbers may be good enough for your use case but from what’s possible with SSDs these numbers aren’t great. Please note, I mean well. Still a cool setup.

I’d like to see much more latency consistency and 99th even sub ms. Might want to set a latency target with fio and see what kind of load is possible until 99 hits 1ms.

However, I can say all of this but it’s all about context and depending on workload your figures may be totally fine.

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