IJ46541: POTENTIAL UNDETECTED DATA LOSS AFTER RUNNING CHVG -KY OR CHVG -GAPPLIES TO AIX 7200-05

APAR status

• Closed as program error.

Error description

• **************************************************************
  * USERS AFFECTED:
  * Systems running the AIX 7200-05-00 Technology Level with
  * any of the following filesets at or between the given levels:
  * MIN          MAX          FILESET
  * 7.2.5.0      7.2.5.201    bos.rte.lvm
    **************************************************************
  * ERROR DESCRIPTION:
  * Potential undetected data loss can occur on disks larger than
  * 2 TB if 'chvg -ky' is run to make the VG encryption capable,
  * or if 'chvg -g' is run on a VG that is encryption capable.
  *
  * On AIX 7.3, VGs are created as encryption capable by default.
  * For encryption capable VGs, 'lsvg <vgname>' will show:
  * ENCRYPTION:         yes
  *
  * If the 'chvg' commands above are run, a variable size block
  * of LVM metadata can overwrite user data on disks in the VG
  * that are larger than 2 TB.
  * This can occur during the chvg command execution, and also
  * could reoccur later if the metadata is updated on disk.
    **************************************************************
  * RECOMMENDATION:
  * Avoid the above 'chvg' commands until the following fix has
  * been applied.
  * Install APAR IJ46541.
  * Prior to fix availability, an interim fix is available from
  * either
  * ftp://aix.software.ibm.com/aix/ifixes/ij46487/
  * https://aix.software.ibm.com/aix/ifixes/ij46487/
  * Installation of the ifix does not require a reboot.
    **************************************************************
  

Local fix

Problem summary

• Potential data loss can occur on disks larger than 2 TB
  if 'chvg -ky' is run to make the VG encryption capable, or
  if 'chvg -g' is run on a VG that is encryption capable.
  
  On 7.3, VGs are created as encryption capable by default.
  For encryption capable VGs, 'lsvg <vgname>' will show:
  ENCRYPTION:         yes
  
  If the commands above are run, a variable size block of LVM
  metadata can overwrite user data on disks in the VG that are
  larger than 2 TB.
  This can occur during the chvg command execution, and also
  could re-occur later if the metadata is updated on disk.
  

Problem conclusion

• Correct calculation done in chvg code to not overflow with
  > 2TB disks.
  

Temporary fix

•   *********
    * HIPER *
    *********
  

Comments

• 7200-05 - use AIX APAR IJ46541
  7300-00 - use AIX APAR IJ46487
  7300-02 - use AIX APAR IJ46543
  

APAR Information

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

  IJ46487

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

Fix information

• Fixed component name

  AIX V7.2

• Fixed component ID

  5765CD200

Applicable component levels