A potential for data loss has been discovered in NetBackup 6.5GA - 6.5.4. Using the bpexpdate command with the -stype (server type) switch can expire image copies that were not requested to be expired.

Problem

A potential for data loss has been discovered in NetBackup 6.5GA - 6.5.4. Using the bpexpdate command with the -stype (server type) switch can expire image copies that were not requested to be expired.

Solution

Introduction:
A potential for data loss has been discovered in NetBackup 6.5GA - 6.5.4.  Using the bpexpdate command with the -stype (server type) switch will expire all image copies specified, but will also expire all other copies of these images, even if these image copies are kept in other locations such as tape, or other storage server types.  All copies of any images encountered will be expired. This issue affects all expirations using bpexpdate with the -stype switch (via command line or script).  This issue occurs whether the -stype switch is used alone, or along with other switches.  


What is affected:
The following versions of NetBackup are affected on all supported Server platforms:

- NetBackup Server / Enterprise Server 6.5GA through 6.5.4


How to determine if affected:
Image copies can be expired incorrectly if ALL of the following conditions are met:
- A NetBackup Server is running one of the versions above on a supported platform
- The bpexpdate command is run from the command line on the server, using the -stype (server type) switch.  
Note: The -stype switch applies to server types that include Advanced Disk or OST (OpenStorage). (Note that this can affect PureDisk storage pools).
- The above command successfully expires images.
- Additional copies exist of the image(s) expired with this command, but are outside of what was specified to be expired.

If the command executes successfully, all applicable images are removed.  However, due to this issue all other copies also removed regardless of whether they reside on another volume, server, storage unit or storage unit type.  Therefore, if any image has at least one copy affected by the command, all copies of this image are expired.


Example:
Suppose that a backup image has 3 copies.  Copy 1 is on Tape, Copy 2 is on "DiskVolume1" and Copy 3 is on "PureDiskVolume".  Suppose it is desired that backups be expired from the PureDisk volume with the following command in order to free disk space:

bpexpdate -stype PureDisk -dp dskpool73 -dv PureDiskVolume

This command will expire all image copies on PureDiskVolume.  However, due to this issue, all other copies at other locations are also expired.  Therefore, the tape copy of this image is expired as well as the copy on another OST volume called DiskVolume1.

The affected switch is -stype (note that the -dp and -dv switches require -stype).  Therefore, the following bpexpdate syntaxes are also affected by this issue:

bpexpdate -stype PureDisk -dp dskpool73
Result: (all images in the dskpool73 disk pool (and all its volumes) will be expired.  All copies of these images will also be expired, even if the copies exist on a disk pool other than dskpool73)

bpexpdate -stype PureDisk
Result: (all images found on any PureDisk Server Types in the environment will be expired.  All copies of these images will also be expired, even if the copies exists on a Server Type other than PureDisk)


Workaround:
If running an affected version of NetBackup, do not use bpexpdate with the -stype switch.  Use a command such as bpimmedia to obtain images as needed.  The same syntax used above for bpexpdate will work with bpimmedia:

bpimmedia -L -stype PureDisk -dp dskpool73 -dv PureDiskVolume

Then, the images given in the output may be expired manually with bpexpdate (WITHOUT -stype).  Be sure to indicate the correct copy number from the bpimmedia output.

bpexpdate -backupid client01_1234567373 -d 0 -copy <copy number>

If this workarounds is not feasible, please contact Technical Support, referencing Etrack 1834450 to obtain a fix.


Formal Resolution:
The formal resolution to this issue (Etrack 1837044) is currently scheduled to be included in the following release:

- NetBackup 6.5 Release Update 5 (6.5.5), scheduled for release in Q4 of calendar year 2009.

When NetBackup 6.5.5 is released, please visit the following link for download and readme information:
 http://www.symantec.com/business/support/overview.jsp?pid=15143

Please note that a formal resolution will prevent future bpexpdate commands from expiring unnecessary data with the -stype switch, but cannot recover data from images that were expired due to this issue.


Best Practices:
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
3. Perform periodic "test" restores
4. Subscribe to technical articles / alerts


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