IBM Support

Tivoli Storage Manager NDMP backups to a NAS-attached tape drive might overwrite the last backup on tape

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Abstract

When an NDMP backup to a NAS-attached drive (device type NAS and storage pool DATAFORMAT NETAPPDUMP, CELERRADUMP, or NDMPDUMP) exceeds 2.1 terabytes in size, the next backup that is written to the same tape might overwrite the last backup on the tape.

Content

Releases Affected:
Tivoli Storage Manager Version 6 and Version 7, all platforms.

Required Conditions:
NDMP backups are configured to store data to a library in which the drives are directly attached to a NAS device. The data is stored in a storage pool with DATAFORMAT set to NETAPPDUMP, CELERRADUMMP, or NDMPDUMP. NDMP filer-to-server backups are not affected. When a new NDMP backup that exceeds 2.1 terabytes is written to tape, the next NDMP backup that is written to the same tape might overwrite the last backup.

Example:

    NDMP Backup 1 stores NAS image 'A' of size 100 GB to tape 'VOL1'
    NDMP Backup 2 stores NAS image 'B' of size 2.5 Terabytes to tape 'VOL1'
    NDMP Backup 3 stores NAS image 'C' (size is unimportant) to tape 'VOL1'
    The second backup of image 'B' might be overwritten by the third backup of image 'C'.

The Perl script "chkit04486v21.pl" that is attached to this document lists the volumes and NDMP backup images that are affected by this error. The script lists the bitfile identifier, node name, file space name, and backup date for each affected NDMP backup.

Before you run the script, edit it. Set the following two variables for your database:
my $instance        = "tsminst1";     # DB2 instance name, if your
                                      # DB2INSTANCE environment variable is set it
                                      # will override this value
my $dbalias         = "tsmdb1";       # DB2 database alias for TSM database


The following example is a sample output from the Perl script chkit04486v21.pl:
H:\sb\77887>chkit04486v21.pl
**********************************************************************
* (C) Copyright IBM Corporation 2014, 2014.  All rights reserved.    *
*                                                                    *
* Tivoli Storage Manager                                             *
*                                                                    *
* This script searches the database for volumes affected by the      *
* problem described in APAR IT04486:                                 *
*                                                                    *
*   NAS BACKUP TO REMOTE DRIVE EXCEEDS 2.1 TERABYTES IS OVERWRITTEN  *
*                                                                    *
* This script searches the database for volumes containing NAS       *
* backup data in which a backup image might have been overwritten.   *
* See http://www-01.ibm.com/support/docview.wss?uid=swg21684855      *
* for the latest version of the script                               *
* You need to run the script as instance user with the DB2 env       *
* initialized. The script will prompt you for the necessary          *
* parameters required to run successfully.                           *
*                                                                    *
* Usage: H:\sb\77887\chkit04486v21.pl <noprompt>                     *
*                                                                    *
* Dependencies: UNIX or Windows                                      *
*               Perl interpreter installed                           *
*               TSM server installed on the same box                 *
*                                                                    *
* H:\sb\77887\chkit04486v21.pl V2.1                                  *
*                                                                    *
**********************************************************************
Check database manager....
SQL1026N  The database manager is already active.
Collecting data for instance: db711

   Database Connection Information

 Database server        = DB2/NT64 10.1.0
 SQL authorization ID   = MIKE
 Local database alias   = TSMDB1

***********************************************************************
* Running SELECT to find all NAS storage pools ...                    *
***********************************************************************
Number of NAS pools found: 3
NAS pools found:
     VTLPOOL
     NETAPPVTLP
     TIVPOOL

***********************************************************************
* Searching for affected volumes in NAS pools.                        *
***********************************************************************
Searching pool VTLPOOL ...
Pool VTLPOOL has no volumes

Searching pool NETAPPVTLP ...
  *** Volume: VTLDEV12 is affected by APAR IT04486. ***
  *** Volume: VTLDEV15 is affected by APAR IT04486. ***
  *** Volume: VTLDEV16 is affected by APAR IT04486. ***
Pool NETAPPVTLP has 3 volumes affected by APAR IT04486

Searching pool TIVPOOL ...
  *** Volume: MN0811L2 is affected by APAR IT04486. ***
Pool TIVPOOL has 1 volumes affected by APAR IT04486

Total Volumes affected by APAR IT04486 is:  4

**********************************************************************
* Searching affected volumes for overwritten data.                   *
**********************************************************************
No backups on volume VTLDEV12(163) have been overwritten, however the volume should be marked READONLY until all data expires.
No backups on volume VTLDEV15(164) have been overwritten, however the volume should be marked READONLY until all data expires.
No backups on volume VTLDEV16(165) have been overwritten, however the volume should be marked READONLY until all data expires.
NDMP Backup with BFID 64520 at filemark number 10 on volume MN0811L2(169) has been overwritten.
Backup object details: bfId 64520, node name: TIVNAS1A, filespace: /vol/vol6, backup date: 2014-10-02-18.56.16.000000
.. End of script.


Problem Resolution:
Apply the fix level when available. This problem is fixed in Tivoli Storage Manager server levels 6.2.7, 6.3.5.100, 6.3.6, 7.1.1.1, and 7.1.2 and later for all server platforms. 

Circumvention:
  1. If an NDMP backup image is over 2.1 terabytes, update the volume access to READONLY. This update prevents new backups from being written to the tape.
  2. Use NDMP filer to server backup until a fix level is applied.
  3. If you are backing up to a virtual tape library, define the tape capacity to a value less than 2.1 terabytes.

Perl script to identify affected NDMP data: chkit04486v21.plchkit04486v21.pl

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Document Information

Modified date:
25 September 2022

UID

swg21684855