Potential undetected loss of incrementally restored DS8000 Safeguarded Copy data

Notification

Risk classification

HIPER (High Impact and/or Pervasive)

Risk categories

Data Loss

Affected Domain

DS8A00 and DS8900F systems using Space Release and Safeguarded Copy (SGC), when incrementally restored.

Abstract

Undetected data loss is possible with systems running Space Release in conjunction with SGC incremental restore function.

Description

Undetected data loss is possible with systems running Space Release in conjunction with SGC incremental restore. Incremental restore of a SGC backup may fail to restore all data even though all required data is preserved in the SGC backup and the data on the SGC Recovery Volume is valid, correct and complete. Complete restoration of all required data can be achieved by performing a full restore of the SGC backup; a full restore requires adjusting the CSM and/or GDPS restore procedure as described below.

Recommended Action

Mitigation:
There are three ways to mitigate:

Option A: Use Incremental Restore

SGC copy backups taken after the last space release can be incrementally restored.

Option B: Full Restore
If using Space Release in conjunction with SGC, any backup can be used with a full restore.
Please note that a full restore will take longer than an incremental restore.

Customers using CSM need to set the following properties to ensure a full restore:

From Settings-> Server Properties, click on Edit button.
Add the following properties to Server Properties
csm.session.disable_sgc_incremental_recovery_bit=true
csm.server.obm_poller_disabled=true
Click Save.

Customers using GDPS: Install the PTF for APAR PH66346, GDPS 4.6, 4.7, and 4.8: UO03093, UO03092, UO03091, respectively, and contact IBM GDPS support for further instructions.

Option C: Do not use Space Release:
If sufficient free space is available, customer can stop using space release. However, any backups performed prior to this action will require a full restore.

Fix:
An enhancement has been delivered in the following bundles:
DS8A00: R10.1 GA - 10.10.106.0
DS8900F: R9.4 SP4 - 89.44.4.0

Reference ID

372800

Date first published

14 May 2025

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