IBM Support

Info Letter: TS7740 (3957-V07) and TS7720 (3957-VEB) code update considerations for R4.0 PGA1 (8.40.1.16) or higher and R4.1.1 (8.41.100.15) or higher.

Preventive Service Planning


Abstract

The R4.0 PGA1 (8.40.1.16) or higher and R4.1.1 (8.41.100.15) or higher release of TS7700 microcode contains various improvements that increase the reliability of the TS7700 backend disk cache through improved error handling. These reliability improvements may result in minor degradations in TS7700 throughput for those customers whose operational throughputs are disk cache constrained. .

Content

Affected hardware configurations (models V07 and VEB)

  • TS7740 - All
  • TS7720 - Only those in a grid operating in an Active-Active Rewind Unload (Immediate mode) bi-directional replication configuration are effected.

Explanation of potential performance impact

When Processing compressible data (2.66:1) while the disk cache is constrained may result in sustained throughput reductions up to 10%. If running uncompressible data, write reductions up to 16% may be experienced.

How to verify if disk cache constrained

The 3-month VEHSTATS for the most I/O intensive batch windows (e.g. quarter-end processing) should be reviewed. If the VEHSTATS analysis of those batch windows indicate that the average cache utilization is greater than or equal to 90% utilization, then this release of microcode will likely extend those batch windows.

Should I upgrade?

If it is determined your environment is not exposed to a performance impact, it is safe to upgrade.
If it is determined your environment is exposed to a performance impact and it does not jeopardize your batch window, it is safe to upgrade.
If it is determined your environment is exposed to a performance impact and it jeopardizes your batch window, it is not recommended to upgrade.

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Cross reference information




Tape Storage
TS7700 virtual tape systems



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Document Information

Modified date:
17 June 2018

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ssg1S1009599