When restoring a subset of data from a backup set that is larger than 4 terabytes (TB), the restore would say successful even though all the data was not restored

Problem

When restoring a subset of data from a backup set that is larger than 4 terabytes (TB), the restore would say successful even though all the data was not restored

Solution

In Backup Exec 12 or earlier versions, it was found that under a certain sub-set restore condition (not restoring the whole set) the restore would actually complete successfully but the byte count was too low and some of the file data was not restored.

How to Know if You are Affected:
 
  • The backup is of a single volume containing over 4 TB  of data
  • The restore is a sub-set (not the whole restore set)
  • The restore selection must start  prior to the 4 TB point and end at or after the 4 TB mark in the backup set
 
Explanation of the issue:
When having a backup set totaling more than 4 TB (terabytes) it was deemed important to test backup and restore problems with regular file system backups. It was found that under a certain sub-set restore condition (not restoring the whole set) the restore would actually complete successfully but the byte count was too low and some of the file data was not restored.

Final Resolution:
Set the registry value "use fast file restore" to '0' for the duration of the restore. The registry key is located here:

HKLM/Software/Symantec/Backup Exec For Windows/Backup Exec/Engine/Tape Format

Warning: Incorrect use of the Windows registry editor may prevent the operating system from functioning properly. Great care should be taken when making changes to a Windows registry. Registry modifications should only be carried-out by persons experienced in the use of the registry editor application. It is recommended that a complete backup of the registry and workstation be made prior to making any registry changes.
 

Terms of use for this information are found in Legal Notices.

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