Re: SSD Sizing for DB/WAL: 4% for large drives?

Burkhard Linke <Burkhard.Linke@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx> · Wed, 29 May 2019 08:42:58 +0200



    Hi,

    
    On 5/29/19 8:25 AM, Konstantin Shalygin
      wrote:

    
        We have a similar setup, but 24 disks and 2x P4800X. And the 375GB NVME 
drives are _not_ large enough:

      
    *snipsnap*

    
        Your block.db is 29Gb, should be 30Gb to prevent spillover to
        slow backend.
    
    
    Well, it's the usual gigabyte vs. gigibyte fuck up.....
    

    The drive has exactly 366292584 bytes, which is ~350GB (with GB =
      the computer scientist's GB, 1024^3). Since rocksdb also seems to
      be written by computer scientists, we are 10 GB short for a
      working setup...
    

    There are options to reduce the level size in rocksdb. Does
      anyone have experience with changing them, and what are sane
      values (e.g. powers of 2)?
    

    Regards,
    Burkhard
    

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