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Potential performance impact using zHyperLink writes on 89.40.83.0 or 89.40.89.0 Bundles

Notification


Risk classification

HIPER (High Impact and/or Pervasive)

Risk categories

Severe Performance Impact

Affected Domain

DS8900F systems running 89.40.83.0 or 89.40.89.0 Bundles

Abstract

DS8900F systems running 89.40.83.0 or 89.40.89.0, and using zHyperLink write, combined with FICON (zHPF) read workloads, may experience performance impacts.

Description

While a zHyperLink (zHL) write chain is being processed, aggressive zHPF read operations are allowed to interrupt the zHL write chain, to read the same track that is in the process of being written.  Once interrupted, zHL access is not re-obtained, and the interrupted write activity is then performed using zHPF, reducing the synchronous write success rates.

Reference ID

365231

Date first published

23 September 2024

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Document Information

Modified date:
23 September 2024

UID

ibm17168984