Deduplication of large files on Tivoli Storage Manager Version 6.1 and 6.2 may cause active log to run out of space.

Flash (Alert)


Abstract

Analyzing very large files in a deduplicated storage pool on Tivoli Storage Manager Version 6.1 and 6.2 may cause the active log to run out of space or cause other sessions or server processes to stall.

Content

Problem:
The active log for a Tivoli Storage Manager Version 6.1 or 6.2 server might run out of space when an Identify Duplicate process is analyzing a file that is hundreds of gigabytes or larger. These files can have several million extents. Each extent is represented in the database and is stored in the active log until the database entries are committed. Because of the large number of extents, it is likely that the active log will run out of space.

A side-effect of this problem is that client sessions or server processes might stall until the Identify Duplicates process that is analyzing the large file finishes. Analyzing large files holds resources such as locks and volumes until the Identify Duplicates process is completed. This prevents other sessions and processes from acquiring these resources and causes them to have to wait. The stall could last anywhere from several hours to days, depending on the size of the file being analyzed.

Who is affected:
Tivoli Storage Manager Version 6.1 and 6.2 users who store very large files into storage pools that have deduplication enabled.

Recommendation:
Use the following circumventions or upgrade to Tivoli Storage Manager 6.3.

Circumvention:

  • If the storage pool with deduplication enabled has a NEXTSTGPOOL defined, customers can use the MAXSIZE parameter to prevent very large files from being stored in the deduplicated storage pool. Bypassing the deduplicated storage pool prevents large files from being analyzed and causing the problems described in this flash. A recommended value for MAXSIZE is 50G.
  • If an Identify Duplicates process begins processing a very large file, issue the QUERY PROCESS command and find the process. Note the volume that the process is currently analyzing. Cancel all Identify Duplicates processes and update the volume to make its status UNAVAILABLE. This will prevent future Identify Duplicates process from selecting the volume. If the volume is needed for a client restore or retrieve, cancel any Identify Duplicates processes running at the time and update the volume status to READONLY. Once the client restore/retrieve has completed, update the volume status to UNAVAILABLE again and resume the Identify Duplicates processes as needed. Once the fix has been applied, update the status of any volumes that were made UNAVAILABLE to READONLY . The Identify Duplicates processes will then begin processing any files on the volumes that have not already been analyzed.


Cross reference information
Segment Product Component Platform Version Edition
Storage Management Tivoli Storage Manager Server Platform Independent 6.1 All Editions

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Document information


More support for:

Tivoli Storage Manager
Server

Software version:

6.1

Operating system(s):

Platform Independent

Reference #:

1408187

Modified date:

2010-09-24

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