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IV15028: VFC CLIENT DRIVER SEES HIGH H_DROPPED ERRORS WITH HEAVY LOAD APPLIES TO AIX 6100-07

A fix is available

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APAR status

  • Closed as program error.

Error description

  • On the client:
    
    The first instance of DMA_ERR revolves around a failed
    attempt at sending an I/O request to the VIOS:
    
    492  h_call: start H_PUT_TCE iar=3F85CFC p1=1000000C
         p2=2F8000  p3=14742FA001
    492  h_call: start H_XIRR iar=3F64F88 p1=19ECD50
         p2=1D55526F0C7800 p3=0000
    492  h_call: end H_XIRR iar=3F64F88 rc=0000
    492  h_call: end H_PUT_TCE iar=3F85CFC rc=0000
    492  h_call: start H_PUT_TCE iar=3F85CFC p1=1000000C
         p2=2F9000 p3=14742FB001
    492  h_call: end H_PUT_TCE iar=3F85CFC rc=0000
    492  h_call: start H_SEND_CRQ iar=3F9E25C p1=84C099
         p2=1D55526F0C85A4 p3=0000
    492  h_call: end H_SEND_CRQ iar=FFFFFFFFFFFFFFF4
         rc=3F9E25C
    492  h_call: start H_PUT_TCE iar=3F80AA8 p1=1000000C
         p2=2F8000 p3=100C120000340000
    492  h_call: end H_PUT_TCE iar=3F80AA8 rc=0000
    492  h_call: start H_PUT_TCE iar=3F80AA8 p1=1000000C
         p2=2F9000 p3=100C120000340000
    492  h_call: end H_PUT_TCE iar=3F80AA8 rc=0000
         1D1  ERRLG errput: error id=00000000C8BAC8C9
    
    The attempt at H_SEND_CRQ failed with H_DROPPED.
    From code inspection of vfc_issue(), if H_SEND_CRQ
    fails with H_DROPPED, we should unmap dma resources,
    and return the request to the head of the pending
    queue for a retry.
    

Local fix

Problem summary

  • When the Virtual Fibre Channel adapter attribute num_cmd_elems
    is increased from its default 200 to something like 512 or
    higher, then under heady IO load, a lot of H_DROPPED errors
    can be seen against H_SEND_CRQ PHYP calls in traces. There
    could also be IO errors.
    

Problem conclusion

  • VFC Client driver code modified to have proper flow control
    so that it does not overrun the Server receive queue. This
    will prevent the H_DROPPED errors coming up repeatedly.
    

Temporary fix

Comments

APAR Information

  • APAR number

    IV15028

  • Reported component name

    AIX 610 STD EDI

  • Reported component ID

    5765G6200

  • Reported release

    610

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Submitted date

    2012-02-06

  • Closed date

    2012-02-06

  • Last modified date

    2013-04-09

  • APAR is sysrouted FROM one or more of the following:

    IV12883

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    AIX 610 STD EDI

  • Fixed component ID

    5765G6200

Applicable component levels

  • R610 PSY U839521

       UP12/05/11 I 1000

PTF to Fileset Mapping

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Document Information

Modified date:
09 April 2013