Introduction
This issue affects the following NetBackup versions on all supported operating systems:

-Veritas NetBackup (tm) Enterprise Server 5.1 Maintenance Pack 3
-Veritas NetBackup (tm) Server 5.1 Maintenance Pack 3

This issue affects all Master or Media server installations running NetBackup 5.1 Maintenance Pack 3 (MP3) Server patch.  This issue is specific to the bptm daemon which is bundled in the NetBackup 5.1 MP3 Server pack.


How to Determine if Affected
Verify the NetBackup Maintenance Pack level on the Master server and Media server(s).  If NetBackup 5.1 Maintenance Pack 3 is installed and ALL of the following conditions are true, there is a possibility for data loss to occur:

1. The original backup image must be written to tape.  Virtual Tape Libraries (VTL) will be affected by this as well.  Disk based backups are not affected by this issue.

2. The original backup image must span more than one fragment. This would be caused when multiplexing is enabled, when a backup image spans more than one tape, when the maximum fragment size is reached, or when a checkpoint occurs for checkpoint-restart backups.

3. Lastly, the image must be a duplicate.

If the criteria above apply, then the second and subsequent copies of backup images created by the duplicate operation may be written incorrectly.  Restores from these copies may result in some amount of data loss, the amount of which is related to the number of fragments involved and the size of the files in the backup image itself.  

For example, when restoring from a file server backup image which consists of hundreds or thousands of files, those files that cross the fragment boundary in the image will be affected, but the rest of the restored files will not be affected.  The greatest concern is for environments in which the original copy is expired quickly, such as when using a virtual tape library (VTL) as a staging area for backup operations.  The original copy on the VTL was written correctly, but expired soon after the second and subsequent copies were made; therefore, at least some of the data has been lost.


What is not affected?
1. Disk based backups are not affected by this issue.
2. The original backup copy written to tape is not affected by this issue. Therefore, the original backup image can be used for restores successfully.


Workarounds
1. If a restore is needed, perform the restore using the original backup image.  This will allow for a complete recovery of the image, in its entirety.

2. Please contact Symantec Technical Services for a workaround to prevent impacting additional backup images.  This workaround is only a temporary fix until the formal resolution, listed below, can be applied.  To contact Symantec Technical Services, refer to the following link:
 http://support.veritas.com/phonesup/phonesup.htm

Formal Resolution
This issue is formally resolved with NetBackup 5.1 Maintenance Pack 3A and is available on the Download section of the Support Web site:    http://support.veritas.com/menu_ddProduct_NBUESVR_view_DOWNLOAD.htm . These maintenance packs can also be found below, in the "Related Documents" section.

Note: The NetBackup 5.1 MP3 Japanese localization pack, Database Agents and Options are not affected by this and can be installed on top of the NetBackup 5.1 Maintenance Pack 3A.


Symantec strongly recommends the following best practices:
1.  Always perform a Full backup prior to and after any changes to your environment.
2.  Always make sure that your environment is running the latest version and patch level.

If you have any questions or concerns about this issue, please contact Symantec Technical Support.

If you have not received this TechNote from the Symantec Email Notification Service for Software Alerts, please subscribe at the following link:      http://maillist.support.veritas.com/subscribe.asp