Re: Slow rbd reads (fast writes) with luminous + bluestore

Emmanuel Lacour <elacour@xxxxxxxxxxxxxxx> · Mon, 13 Aug 2018 16:44:30 +0200



    Le 13/08/2018 à 16:29, Jason Dillaman a
      écrit :

    
          For such a small benchmark (2 GiB), I wouldn't be
            surprised if you are not just seeing the Filestore-backed
            OSDs hitting the page cache for the reads whereas the
            Bluestore-backed OSDs need to actually hit the disk. Are the
            two clusters similar in terms of the numbers of HDD-backed
            OSDs?
          

    I looked at iostat on both cluster when running fio and yes, on new
    cluster I see disks reads, but not with old cluster, everything
    comes from page cache.

    
    So is there a way to simulate page cache for bluestore, or on rbd
    side?

  
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