A Duplicate Job to Tape from a GRT enabled backup set on Disk may take a long time to complete.

Problem

A Duplicate Job to Tape from a GRT enabled backup set on Disk may take a long time to complete.

Error Message

The GRT Backup to Disk takes less time compared to the delayed catalog Job and Duplicate Backup to tape.

Note : The performance of delayed catalog Job and duplicate to tape (in case of GRT Backup Set) operations will differ according to the size, content, where does the source reside, number of items in the Backup set etc. The delayed catalog job run time will also depend on if the backed up set is the first incremental/differential or 2nd or 3rd.

Cause

What happens when GRT Backup is targetted to Disk or Tape or Duplicated from disk to Tape.

Case 1 - A GRT backup to disk, using instant GRT

1) Performs a Backup of Database/Virtual Machine.
2) Enumeration of all the items in the Backed up set is not performed because it is not needed. During restore the browse of these individual items is done dynamically when the backup set is on disk.

Case 2 - A GRT Backup to Tape

1) Performs a Backup of Database/Virtual Machine.
2) All the content which is Backed up is enumerated and catalog is created. This can take substantial time if there are a lot of items in the Database/Virtual Machine.

Case 3 - A Duplicate job from Disk to Tape when Backup is done with Instant GRT.

1) Performs a Duplicate of the database which was backed up to Disk
2) During the Duplicate job to Tape it will enumerate and catalog all the items that are present in the backup set that was part of the primary backup. Hence this will take longer than a GRT Backup to Disk with instant GRT.

Case 4 - Duplicate to Tape when primary set was backed up with delayed catalog setting selected.

1) If the GRT enabled Backup Job is set to run a Delayed catalog job then a full catalog is performed on a backup to disk set.
2) The duplicate job to tape does not use this catalog and instead performs another full catalog of the GRT items. Hence this will take longer than a GRT Backup to Disk with instant GRT.

Note: The duplicate to tape performance from disk (GRT set) in Case 3 and 4 does not change if instant GRT or delayed catalog is selected in the Primary Backup Job Settings.

For more details about Instant GRT and Full Catalog (Delayed catalog) refer the admin guide topic "Configuring Instant GRT and full catalog options to improve backup performance for GRT-enabled jobs"

Solution

Workaround :
If GRT duplicate Backup performance to Tape is a concern then Backup can be performed straight to Tape with the GRT settings unchecked in the Backup Job. This way the additional catalog phase can be avoided. This is applicable to any Backup where GRT is enabled in the primary Backup Job.

Note: The downside to this (GRT disabled during backup) is (lets consider Exchange database backup for example), individual items restore will need to be performed by restoring the Backed up database to an Exchange recovery database and then the needed individual items can be recovered from there. Additional space will be needed on Exchange server if restore of backed up exchange database has to be done using the recovery database method. Another example would be, If a non GRT backup of VMware or Hyper-V virtual machine is taken on Tape, then entire VM will need to be restored else to restore individual files, restore the vmdk or vhdx to local BE server and then mount it on ESX or Hyper-V host and recover the individual items needed.
 

Veritas Technologies LLC has acknowledged that the above-mentioned issue is present in the current version(s) listed under the Product(s) Section of this article. Veritas Technologies LLC is committed to product quality and satisfied customers.

There are currently no plans to address this issue by way of a patch or hotfix in the current or previous versions of the software at the present time. This issue may be resolved in a future major revision of the software at a later time. However, this particular issue is not currently scheduled for any release.  If you feel this issue has a direct business impact for you and your continued use of the product, please contact your Veritas Sales representative or the Veritas Sales group to discuss these concerns.  For information on how to contact Veritas Sales, please see https://www.veritas.com