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  1. Documentation
  2. DOCS-9228

3.0 Wired Tiger cache utilization documentation needs to say it rounds down to the closest whole integer value of GB

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    Details

    • Type: Improvement
    • Status: Open
    • Priority: Major - P3
    • Resolution: Unresolved
    • Affects Version/s: None
    • Fix Version/s: None
    • Component/s: manual, Server
    • Labels:

      Description

      I have confirmed the behavior with the Wired Tiger development team. By default, the Wired Tiger cache will be set to a rounded down whole integer value GB. In your system, we see that the memory configured is

      ```
      MemTotal: 8057784 kB
      ```

      50% of this is 4028892 KB =~ 3.8GB. This gets rounded down to 3GB.

      See the following:

      ```
      > db.adminCommand(

      { "setParameter": 1, "wiredTigerEngineRuntimeConfig": "cache_size=3.7G"}

      )

      { "was" : "", "code" : 2, "ok" : 0, "errmsg" : "WiredTiger reconfiguration failed with error code (22): Invalid argument" }

      ```

      This shows that the parameter needs to be a whole integer value.

      ```
      > db.adminCommand(

      { "setParameter": 1, "wiredTigerEngineRuntimeConfig": "cache_size=4G"}

      )

      { "was" : "", "ok" : 1 }

      ```

      We should clarify that we aren't actually using 50% in 3.0.

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            Assignee:
            kay.kim Kay Kim (Inactive)
            Reporter:
            shakir.sadikali Shakir Sadikali
            Participants:
            Last commenter:
            Kay Kim Kay Kim (Inactive)
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              Dates

              Created:
              Updated:
              Days since reply:
              4 years, 47 weeks ago
              Date of 1st Reply: