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IV56892: CRASH IN HD_BEGIN WITH SYNCVG -F -P OF STRIPED LV APPLIES TO AIX 6100-09

A fix is available

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APAR status

  • Closed as program error.

Error description

  • syncvg -f -P on a VG with striped LV may cause system to
    crash in hd_resyncpp, with a stack similar to:
    [05C948CC]hd_begin+0000CC
    [05C9A4C8]hd_resyncpp+0001E8 (??)
    [05C94CE8]hd_end+000168 (??)
    [00221A40]percpu_iodone_offl+0000E0 (??)
    [00221068]iodone_offl+0000C8 ()
    
    This will only happen for a 3 copy striped LV, where
    one copy is stale and a forced parallel resync is done.
    
    
    Also syncvg -f -P of a striped LV (either 2 or 3 copies)
    may not leave the mirror copies fully syncd after
    completion.
    

Local fix

  • Run syncvg -f without -P
    

Problem summary

  • With certain timing, when doing a forced sync of a striped LV
    with multiple parallel threads (using syncvg with -f and -P
    on a striped LV)...
    There is a single field in the LVM kernel extension that tracks
    which copy needs to be syncd.
    In the scenario above, striped LVs can cause multiple syncs
    to be running in parallel for the same LP, which use the same
    field to track their sync progress.
    One thread stomping on this during another thread's use of it
    can lead to the crash due to invalid mirror mask.
    

Problem conclusion

  • Enhance the logic of parallel sync so that for striped LVs it
    will give each thread a whole stripe to sync, and not allow
    2 threads to sync the same stripe (same LPs) at once.
    

Temporary fix

Comments

  • 6100-07 - use AIX APAR IV58385
    6100-08 - use AIX APAR IV58052
    6100-09 - use AIX APAR IV56892
    6100-09 - use AIX APAR IV56892
    6100-09 - use AIX APAR IV56892
    7100-01 - use AIX APAR IV57697
    7100-02 - use AIX APAR IV56348
    7100-03 - use AIX APAR IV56889
    7100-04 - use AIX APAR IV56905
    

APAR Information

  • APAR number

    IV56892

  • Reported component name

    AIX 610 STD EDI

  • Reported component ID

    5765G6200

  • Reported release

    610

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Submitted date

    2014-03-20

  • Closed date

    2014-03-20

  • Last modified date

    2016-05-10

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

    IV56348

  • 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 U859282

       UP14/05/21 I 1000

PTF to Fileset Mapping



Document information

More support for: AIX Standard Edition

Software version: 610

Operating system(s): AIX

Reference #: IV56892

Modified date: 10 May 2016