reducevg very slow

This is an APAR, but really it’s a description. Reducevg sends the equivalent of TRIM commands, but on a storage array, this is writing nulls. On a big LUN, or with a busy array, this can take a long time. If you do not need to worry about this, then you can disable that space reclaim.

ioo -o -dk_lbp_enabled=0

Here is the IBM doc about it.

 

IJ23045: REDUCEVG UNCLEAR ON DELAY WHEN WAITING FOR INFLIGHT RECLAIM REQ APPLIES TO AIX 7100-05

 

A fix is available

APAR status

  • Closed as program error.

Error description

  • reducevg may be unclear, why there is some delay
    when waiting on inflight reclaim requests.
    

Local fix

  • Disable space reclamation by running:
    ioo -o dk_lbp_enabled=0
    

Problem summary

  • reducevg may be unclear, why there is some delay
    when waiting on inflight reclaim requests.
    

Problem conclusion

  • reducevg displays message incase there are space reclamation
    IOs inflight to indicate reducevg may take some time to
    complete.

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