VM66342: PEVM66098 LINUX QUERY FOR ESE VOLUME FUNCTION FAILS 19/11/09 PTF PECHANGE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• A Linux guest issues a device dependent query I/O to determine
  if a FICON ECKD DASD has the Z Thin Provisioning Extent Space
  Efficient capability.   This query is designed to work on
  a attached DASD, 0-END minidisk, & 1-END minidisk.   Testing
  discovered that the query fails on a 1-END minidisk.  Linux
  therefore doesn't exploit its Thin Provisioning capabilities
  on a 1-END minidisk (when it otherwise could).
  

Local fix

• Use 0-END minidisk until fix is available.
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: All z/VM users of 1-END Minidisks that       *
  *                 exploit DS8000 (or like) Extent Space        *
  *                 Efficient (ESE) Volume functions.            *
  ****************************************************************
  * PROBLEM DESCRIPTION:                                         *
  ****************************************************************
  * RECOMMENDATION: APPLY PTF                                    *
  ****************************************************************
  z/VM supports special purpose DS8000 Thin Provisioning Extent
  Space Efficient (ESE) I/O functions issued to Dedicated DASD,
  Real Cylinder 0-to-END Minidisks, and Real Cylinder 1-to-END
  Minidisks.
  
  This APAR addresses 2 problems experienced by Linux guests in
  their exploitation of the ESE I/O functions on 1-to-END
  minidisks.  These problems are also possible if z/VM or z/OS is
  running as a guest.  The problems do not occur on Dedicated DASD
  or 0-END minidisks.
  
  1. The I/O function to query the ESE capability of a DS8K LSS is
  rejected by VM CCW Translation when issued to a 1-END minidisk.
  The guest determines that the LSS and its DASD are not capable
  of ESE and gates all further exploitation.
  
  2. The I/O to return extents back to the free pool is allowed on
  a 1-END minidisk, but releases extents associated with real
  cylinder 0.  This can cause a guest that performs a ESE Space
  Release function on a 1-END minidisk to destroy the Volume Label
  and VTOC (or Allocation Map) on Real Cylinder 0.
  

Problem conclusion

• PEVM66098 VM66098 VM CCW Translation was modified to correct the
  2 problems with ESE I/O functions issued from a guest to 1-END
  minidisks.
  
  1. HCPMD_ was modified to allow the ESE Query to properly
  function on a 1-END minidisk.
  
  2. HCPMD_ was modified so that an ESE Space Release issued to
  guest cylinder 0 is relocated to Real Cylinder 1.  This avoids
  releasing extents on Real Cylinder 0.
  

Temporary fix

• FOR RELEASE VM/ESA CP/ESA R640 :
  PREREQ: VM66267 VM66098
  CO-REQ: NONE
  IF-REQ: NONE
  FOR RELEASE VM/ESACP/ESAR710 :
  PREREQ: VM66267
  CO-REQ: NONE
  IF-REQ: NONE
  

Comments

APAR Information

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

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

  UM35620 UM35621

Modules/Macros

• HCPMD3   HCPMD5
  

Fix information

• Fixed component name

  VM CP

• Fixed component ID

  568411202

Applicable component levels

• R640 PSY UM35620

     UP20/04/07 P 2001 ­

• R710 PSY UM35621

     UP20/04/07 P 2101 ­

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.