TECH ALERT: If a retention level is set such that image expiry dates are after January 2038, after successful backups/duplications to tape using the retention period, the tape media (but not image) is expired. Media may then be overwritten.

  • Modified Date:
  • Article ID:000083437


If a custom retention causes an expiration time to be set beyond UNIX epoch time of Jan 19, 2038 03:14:08 UTC, nbemm does not set the "Data Expiration" date/time and the tape media will expire while the backup image remains in the NetBackup catalog.


For example:

Suppose a tape is in a SCRATCH pool.



At the time of the backup or duplication the media is moved to the assigned volume pool.  However, at the successful conclusion of the backup or duplication, the media will become unassigned and is moved back to the SCRATCH pool. The image remains intact in the images database or catalog.  If the media is unassigned, any media server sharing the media can use that media for another backup or duplication.  When that tape is used a second time, the previous image is overwritten and data loss will occur.



What is affected:

This issue applies to all backup or duplication processes/procedures to tape, including disk storage relocation, storage lifecycle policies (SLP), Vault, manual backup, user backup and command line bpbackup and bpduplicate.


This issue affects the following versions of NetBackup:

  • NetBackup 7.1
  • NetBackup

This issue also affects the following Appliance versions:

  • NetBackup 5200 2.0
  • NetBackup 5220 2.0 

In previous versions of NetBackup, backups or duplications attempted with such a custom retention level would fail with an nbemm error reported.



Error Message

This condition does not provide an error, as the backup/duplication succeeds.  The only way to know if data loss is present is to determine if any retention levels are set high enough to pass the threshold and if they are, run NBCC (linked below).


Future attempts to restore "missing" images which have since been overwritten will fail with an error similar to the following reported in the bptm log:

12:25:32.555 [4572.4892] <16> io_position_for_read: found wrong backup id - otherclient_1213635906: expected someclient_1213635895. 




Use "infinity" retention values instead of custom values which would place expiration dates beyond January 19, 2038 03:14:08 UTC.  (For instance, in 2011, do not set custom retention values greater than 27 years - use "infinity" instead.)



ETA of Fix:

The formal resolution to this issue (Etrack 2443478) is included in the following release:

  • NetBackup 7.1 Maintenance Release 2 (

Please visit the links in the Related Articles section to access download and readme information for NetBackup


This issue is also expected to be addressed in a future NetBackup Appliances version.  When the targeted version is known, this document will be updated.


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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.

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