Netbackup 7.5.0.x backups with multiplexing, multistreaming, and checkpoint restart enabled may hang when a large file is encountered.

Article:TECH194918  |  Created: 2012-08-14  |  Updated: 2013-02-20  |  Article URL http://www.symantec.com/docs/TECH194918
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Article Type
Technical Solution


Environment

Issue



Large (10+ GB) files encountered during backups where multiplexing, multistreaming, and checkpoint restart are enabled may cause bpbkar to detect incorrect file size.  If this happens, bpbrm may wait for bpbkar to complete sending the data indefinitely.


Error



From bpbrm logs we can see the expected size incorrectly identified:
<2> process_cpr_message: CPR - 2162911509 78597 1334668430 1334679283 3965 0 0 1 217586063 1207 1 50 1023 0 750000 0 0 0 145 <backup file path>

From bptm logs the incorrect block size shows:
<2> write_data: Received checkpoint for backup id <backup ID>, calculated blocks: 2162911509 blocks in cpr: 2162911513
<2> write_data: Received checkpoint for backup id <backup ID>, calculated blocks: 2162911509 blocks in cpr: 2162911513

From bpbkar:
<2> bpbkar PrintFile: CPR - 2162911509 78597 1334668430 1334679283 3965 0 0 1 217586063 1207 1 50 1023 0 750000 0 0 0 145 <backup file path>

The block size reported in the above logs is incorrect for the file that we are backing up and will cause the backup to fail to complete.


Environment



  • Large (10 GB+) files included in Backup Selection
  • Multistreaming and multiplexing enabled for the backup job
  • Checkpoint restart enabled

This issue has been reported on NetBackup versions 7.5 through 7.5.0.4.


Cause



bpbkar sent an incorrect file size (expecting 64-bit value but using 32-bit).  This causes an integer overflow and the backup does not receive the correct block count.  As a result, the backup job will hang indefinitely.


Solution



The formal resolution for this issue (Etrack 2783546) is included in the following release:

  • NetBackup 7.5 Maintenance Release 5 (7.5.0.5)

NetBackup 7.5.0.5 is now available - information and download links can be found in the Related Article linked below.

Workaround:
Any of the following reconfigurations of affected policies may be used to work around this issue:

  • Disable multiplexing
  • Disable multistreaming
  • Disable checkpoint restart

If all of these workarounds are unfeasible, please contact Symantec technical support, referencing this document ID and Etrack 2952065 to obtain an Emergency Engineering Binary (EEB) replacement for bpbkar which contains a fix for this issue for NetBackup 7.5.0.4.


Supplemental Materials

SourceETrack
Value2783546
Description

Netbackup 7.5.0.1 with multiplexing and checkpointing enabled, data stops flowing and the backup to tape hangs.




Article URL http://www.symantec.com/docs/TECH194918


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