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Deep/wide directory structures might cause noticeable CPU overhead

Views:
27
Visibility:
Public
Votes:
0
Category:
data-ontap-7
Specialty:
core
Last Updated:

Applies to

All platforms & versions of Data ONTAP

Issue

  • High CPU utilization seen on a storage controller in sysstat -x 1 and sysstat -M 1.
  • A large percentage of blocks read into readahead are directory blocks ((ra.dir_blocks / ra.requested) * 100) in wafl_susp -w:
    ra.dir_blocks = 68624833
    ra.requested = 92736262

(In this case, ~74% of all blocks in readahead during the sample period were directory blocks).

Note: The above two symptoms are not a *definitive* indication that your CPU utilization is caused by directory work; however, it could be.

 

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