When very specific conditions are met within VERITAS NetBackup (tm), data loss is known to occur on one MPX image when using Inline Tape Copy and Multiplexing.

Article:TECH44771  |  Created: 2006-01-21  |  Updated: 2013-10-23  |  Article URL http://www.symantec.com/docs/TECH44771
Article Type
Technical Solution

Product(s)

Environment

Issue



When very specific conditions are met within VERITAS NetBackup (tm), data loss is known to occur on one MPX image when using Inline Tape Copy and Multiplexing.

Error



backup id is not a tar formatted image.

INF - Block number does not match for file , in image is 43038481, in database is 43038992.

INF - Verify of policy , schedule () failed, tar had an unexpected error.

Solution



What is Affected
This issue potentially affects any servers utilizing both the Inline Tape Copy (also displayed as "multiple copies" in the NetBackup Administration Console) and Multiplexing features in the NetBackup versions mentioned below.  This issue affects:
  • NetBackup 4.5, all versions, all supported platforms
  • NetBackup 5.0 and 5.0 MP1 through 5.0 MP5, all supported platforms
  • NetBackup 5.1 and 5.1 MP1 through 5.1 MP3, all supported platforms
  • NetBackup 6.0 all supported platforms
When this issue is encountered, one or more files from a backup in the multiplexed group may not be restorable.

How to Determine if Affected
Data loss is known to occur if ALL of the following conditions are met:
  • Inline Tape Copy is in use, with 2 or more copies configured.
  • AND Multiplexing is enabled, with 2 or more backups active.
  • AND A copy other than first active copy hits the End of Media (EOM).  AND there is a problem allocating or setting the next media for this copy (such as writing the media header) which causes this copy to fail before continuing the other backup(s).
  • AND "Continue if this copy fails" is set for the copy that failed.
  • AND The last buffer written to first active copy, prior to encountering EOM on the failed copy, was not from the first active backup.
When this issue is encountered, the error "not a tar formatted image" will be seen in the problems report, bperror output, restore progress log, and bptm log file when attempting to restore a backup that was part of a multiplexed group.  

The restore progress log will show a message similar to the following:
Error bptm (pid=21134) backup id dataserv01_1122781845 is not a tar formatted image

The bptm log will show an error similar to the following:
<16> filter_image: backup id dataserv01_1122781845 is not a tar formatted image

If the restore fails with the "not a tar formatted image" error message, run a verify on the failing image.
Errors similar to the following may be seen in the verify log or bperror output:
INF - Block number does not match for file <filename>, in image is 43038481, in database is 43038992.
INF - Verify of policy <policy-name>, schedule <schedule-name> (<backup-id>) failed, tar had an unexpected error.

If the "block number does not match" error occurs on verify, please contact Symantec Enterprise Technical Support for further analysis.  Instructions on performing a verify of a backup image are available in the NetBackup System Administrator's Guides, referenced below, in the "Related Documents" section.


Formal Resolution
This issue will be formally resolved in the following NetBackup maintenance packs:

  • VERITAS NetBackup Enterprise Server 5.0, Maintenance Pack 6 (MP6)
  • VERITAS NetBackup Enterprise Server 5.1, Maintenance Pack 4 (MP4)
  • VERITAS NetBackup Enterprise Server 6.0, Maintenance Pack 1 (MP1)
All of these maintenance packs can be found on the following support site:    http://support.veritas.com/menu_ddProduct_NBUESVR_view_DOWNLOAD.htm

Note:  Applying these patches will only prevent future backups from being affected by this issue.  Previously affected backups will not be restorable by NetBackup after applying the packs mentioned herein.   After applying the appropriate patch for your environment, Symantec strongly recommends performing a "Full" backup.

Additional note for NetBackup 4.5 users:  At this time, there are no current plans to issue a patch specifically for the 4.5 code base regarding this issue.  To prevent this issue from occurring in NetBackup 4.5, it will be necessary to perform either of the following actions:
1.  Upgrade to a version and patch level of NetBackup mentioned above in the Formal Resolution section.
2.  Implement one of the workarounds, listed below, in the Workaround section.


Workarounds
Currently, there are 3 known workarounds available:
1.  Do not configure the Inline Tape copies to "continue if this copy fails" in the policy schedule.  Instead, choose to "fail all copies" in the policy schedule.
2.  Discontinue use of the Inline Tape Copy feature in the policy schedule.
3.  Disable Multiplexing on the storage unit that is used.

Details on the configuration of Inline Tape Copy and Multiplexing are available in the NetBackup System Administrator's Guides, referenced below, in the "Related Documents" section.


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 not received this TechNote from the Symantec Email Notification Service as a Software Alert, please subscribe at the following link:

Supplemental Materials

SourceETrack
Value498527
DescriptionEtrack (NetBackup): MPX restore fails wtih "is not a tar formatted image" (image is copy 1 (ITC) copy 2 failed)

SourceETrack
Value498525
DescriptionEtrack (NetBackup): MPX restore fails wtih "is not a tar formatted image" (image is copy 1 (ITC) copy 2 failed)

SourceETrack
Value498524
DescriptionEtrack (NetBackup): MPX restore fails wtih "is not a tar formatted image" (image is copy 1 (ITC) copy 2 failed)

SourceETrack
Value498523
DescriptionEtrack (NetBackup): MPX restore fails wtih "is not a tar formatted image" (image is copy 1 (ITC) copy 2 failed).

SourceETrack
Value498519
DescriptionEtrack (NetBackup): MPX restore fails wtih "is not a tar formatted image" (image is copy 1 (ITC) copy 2 failed)


Legacy ID



280140


Article URL http://www.symantec.com/docs/TECH44771


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