DS8A00 potential undetected data loss on systems running PPRC/Safeguarded Copy, with FCM drives, and Space Release

Notification

Risk classification

HIPER (High Impact and/or Pervasive)

Risk categories

Data Loss

Affected Domain

DS8A00 systems running PPRC/SGC, with FCM drives, Space Release, and the following configured volume sizes:
- For Large Extent Storage Pools:
CKD: 1113 cylinder (MOD 1)
FB: 1 GiB
- For Small Extent Storage Pools:
CKD: 21 cylinder
FB: 16 MiB

Abstract

DS8A00 systems running PPRC/SGC, using FCM drives, and Space Release, may encounter an undetected data loss.

Description

Undetected data loss is possible with systems running PPRC/SGC, using FCM drives, and Space Release.
For volumes in the Affected Domain noted above, an issue in microcode incorrectly releases more space than it should, which results in a loss of data. For fixed block systems, the data loss may go undetected. For CKD volumes, data loss would be detected when the affected data is read.

Recommended Action

Mitigation:
A poke can be set to disable track-level Space Release, until the fix is applied.
To apply the poke ICS, please Contact IBM Support to review the configuration and determine if there is available space to disable track level space release.
Note: After the fix is applied, the poke will need to be removed.

Fix:
R10 SP2.1 10.2.43.0

Reference ID

373384

Date first published

18 June 2025

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