News
Abstract
The R4.2 GA (8.42.0.71) release of TS7700 microcode may exhibit reduced DD peak write performance with Single Active Deferred Copy mode on tape attached systems when utilizing LZ4 or ZSTD compression.
Content
Affected hardware configurations
- TS7740 - Only those in a grid configuration, operating in DD write Single Active Deferred Copy mode, when using LZ4 or ZSTD compression
- TS7720 Tape Attached - Only those in a grid configuration, operating in DD write Single Active Deferred Copy mode, when using LZ4 or ZSTD compression
- TS7760 Tape Attached - Only those in a grid configuration, operating in DD write Single Active Deferred Copy mode, when using LZ4 or ZSTD compression
Explanation of potential performance impact
Peak copy rate of R4.2 GA (8.42.0.71), when processing DD write Single Active Deferred copies, using LZ4 or ZSTD compression, may be reduced up to 8% compared to prior R4.1 Phase 2 (8.41.200.113) level of code.
Note: For additional details concerning TS7700 performance, check out the available whitepaper (here R4.1 Phase 2):
http://www-03.ibm.com/support/techdocs/atsmastr.nsf/WebIndex/WP102751
The references to “D” stand for deferred copy mode. DD represents deferred copies for cluster 0, and deferred copies for cluster 1, so deferred copies for both clusters.
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Document Information
Modified date:
21 September 2018
UID
ibm10732663