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  1. Lustre
  2. LU-10176 Data-on-MDT phase II
  3. LU-10777

DoM performance is bad with FIO write

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    • Rank (Obsolete):
      9223372036854775807

      Description

      FIO test does a lot more RPCs to the MDT with DOM files comparing with OSTs files:

      DOM files:
      WRITE: BW 5900KiB/sec, IOPS 737, lat (7/83624/83631)usec
      ----- MDC RPCs: 118696
      ----- OSC RPCs: 252
      
      OST files:
      WRITE: BW 9738KiB/sec, IOPS 1217, lat (5/47728/47734)usec
      ----- MDC RPCs: 49668
      ----- OSC RPCs: 12302
      

      so there are about 12K IO-related RPCs to the OST and about 70K extra RPCs to the MDT in the same test. That looks like OST writes are cached much better with FIO write pattern than writes to MDT.

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            Assignee:
            tappro Mikhail Pershin
            Reporter:
            tappro Mikhail Pershin
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              Updated:
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