On an alternate client, off-host snapshots back up the local drive instead of the snapshot volume.

Article:TECH197964  |  Created: 2012-10-05  |  Updated: 2012-10-30  |  Article URL http://www.symantec.com/docs/TECH197964
Article Type
Technical Solution


Environment

Subject

Issue



After upgrading NetBackup 7.1.0.3 Alternate Client Host to Release Update 7.1.0.4, off-host snapshots back up the local drive instead of the snapshot volume. This issue occurs when the drive letters or paths are the same on the source and the alternate client.

If the source and alternate clients have the same drive letters or paths, the job tries to protect the data on the alternate client and may exhibit warning messages due to open files on that volume.

It is possible that these jobs may complete with success with a status code 0 reported in the Activity Monitor even though the backup will consist of data from the "wrong" host.

 


Error



In this example from Windows, the same drive letter G:\ was in use on both the client and the alternate client used for off-host snapshots.  A backup on the alternate client was attempted due to this defect.  These errors were found in the bpbkar log on the alternate client:

2:39:04.791 PM: [948.6948] <4> tar_backup_tfi::backup_finishfile_state: INF - catalog message: Dir - 224 16 118 -1 23 16832 root;Administrators@BUILTIN root;SYSTEM@NT:AUTHORITY 0 1338909443 1338909443 1310741500 /G/WAB-DeDUP-Data/data/
2:39:04.791 PM: [948.6948] <2> tar_backup_tfi::backup_startfile_state: TAR - Backup: G:\MyDedupFolder\data\.cnf
2:39:04.791 PM: [948.6948] <4> dos_backup::tfs_readopen: INF - NT Security information obtained for: 'G:\MyDedupFolder\data\.cnf'
2:39:04.791 PM: [948.6948] <4> tar_backup_tfi::backup_finishfile_state: INF - catalog message: Fil - 208 17 123 -1 27 33216 root;Administrators@BUILTIN root;SYSTEM@NT:AUTHORITY 8 1310741523 1338866234 1310741523 /G/WAB-DeDUP-Data/data/.cnf
2:39:04.791 PM: [948.6948] <2> tar_backup_tfi::backup_startfile_state: TAR - Backup: G:\MyDedupFolder\data\.cnt
2:39:04.791 PM: [948.6948] <4> dos_backup::tfs_readopen: INF - NT Security information obtained for: 'G:\MyDedupFolder\data\.cnt'
2:39:04.791 PM: [948.6948] <2> tar_base::V_vTarMsgW: ERR - failure reading file: G:\MyDedupFolder\data\.cnt (WIN32 33: The process cannot access the file because another process has locked a portion of the file. )
2:39:04.791 PM: [948.6948] <4> dos_backup::tfs_readopen: INF - NT Security information obtained for: 'G:\MyDedupFolder\data\.identity'
   

Note: The bpbkar log file is located in the <Install_Path>\NetBackup\logs\bpbkar folder.

 


Environment



This issue affects the following versions of NetBackup:

  • NetBackup 7.1.0.4
  • NetBackup 7.5 through 7.5.0.3

This issue affects policies of policy type MS-Windows, Standard and FlashBackup-Windows where off-host snapshot backups have been configured.  See Figure:

This issue will be seen with Backup Selections which are local fixed (non-removable) drives whose drive letters or paths also exist on the alternate host. 

Example Scenarios:

  • Backup selection is G:\, alternate host has no G:\ drive: backup will work as designed
  • Backup selection is G:\, alternate host also has G:\ drive: backup will be attempted using data from incorrect host, errors similar to above may be displayed
  • Backup selection is G:\somepath, alternate host has G:\ drive but no path G:\somepath: backup will be attempted on the incorrect host, but fail reporting status 71 (none of the files in the file list exist)
  • Backup selection is G:\somepath, alternate host also has path G:\somepath: - backup will be attempted on the incorrect host, errors similar to above may be displayed

Solution



The formal resolution for this issue (Etrack 2835170) is included in the following release:

  • NetBackup 7.5 Maintenance Release 4 (7.5.0.4)

Information on NetBackup 7.5.0.4 can be found in the Related Article linked below

Workaround:
Changing drive letters or paths of Backup Selections or alternate hosts so that none are shared between the client and the alternate hosts resolves this issue - however, this is usually not a feasible solution.

Best Practices:
Symantec strongly recommends the following best practices:
1. Always perform a full DR backup prior to making any changes to your environment.
2. Always make sure that your environment is running the latest version and patch level.
3. Perform periodic "test" restores.
4. Subscribe to technical articles.

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Supplemental Materials

SourceETrack
Value2835170
Description

On the alternate client, MS-Windows offhost backups import the deported snapshot disks from the source node, however bpbkar is reading a local volume mounted under the same drive letter; issue seen after upgrade to 7.1.0.4




Article URL http://www.symantec.com/docs/TECH197964


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