IBM Support

FastBack Data Loss Possible When Protecting Disks 2 TB or larger

Flash (Alert)


IBM Tivoli Storage Manager (TSM) FastBack cannot be used to back up and restore volumes on disks that are 2 Terabytes or larger. Although this limitation is documented, it is not enforced by the product and can result in data loss. The general limitation is also not explicitly documented for Instant Restore or LAN-Free operations.


TSM FastBack does not support monitoring disk I/O activities above a 2 Terabyte (TB) offset during and in between snapshots, as documented in the User Guide and Support Matrix. However, this limitation is not enforced by the product code, which can lead to data loss if such a disk is used with the FastBack repository, Instant Restore volumes, or LAN-Free.
Releases affected:

  • FastBack 5.5
  • FastBack through

Conditions for the problem to occur:
  • Disks being protected by FastBack or being used for Instant Restore of volumes or LAN-Free backups are 2 TB or greater in size
  • I/O operations affecting FastBack occur at or above the 2 TB offset on those disks

How can you tell if you are affected?
Use the Windows Disk Management utility to query the size of the disks being protected by FastBack, and being used for Instant Restore of volumes and LAN-Free backups. If the disks are equal to or larger than 2 Terabytes, you can potentially be affected by this issue.
There is no query and no consistent error messages that show if you actually have been affected.

Do not use disks 2 TB or greater in size for any FastBack functionality.

The 2 Terabyte limitation on disk size will be enforced in the FastBack product beginning with the interim fix level, and will be explicitly documented for Instant Restore and LAN-Free. See APARs IC86652, IC89448, IC89449, and IC89360.

FastBack release levels that allow 2 TB disks to be used First level with 2 TB limitation enforcement within that release through

available now in Fix Central

5.5 Customers that use FastBack version 5.5.x need to upgrade to FastBack version or higher.

Document information

More support for: Tivoli Storage Manager FastBack

Software version: 5.5, 6.1

Operating system(s): Platform Independent

Reference #: 1628277

Modified date: 2013-03-13