About OpenStorage optimized duplication within the same domain

With duplication to another disk appliance within the same domain, the disk appliances manage the deduplication. The ability to duplicate backups to storage in other locations, often across various geographical sites, helps facilitate disaster recovery.

The following are some benefits of optimized, off-host duplication:

Reduced workload on the NetBackup media servers. More backups can be performed.
Faster duplication. Duplication can occur in the background, simultaneously with ongoing backup jobs.
Reduced bandwidth. If the appliance supports deduplication, the copy process may send only changed blocks.

NetBackup supports two optimized duplication methods for OpenStorage. The optimized duplication method that NetBackup uses depends on the capability that the vendor's OpenStorage plug-in exposes, as follows:

Optimized duplication

NetBackup optimized duplication is extent-based; NetBackup transfers data in 256-KB chunks.

For optimized duplication, the NetBackup bpstsinfo command output that shows the storage server capabilities shows the following flag:

STS_SRVC_COPY_EXTENT

Whole image optimized duplication

Whole image optimized duplication uses the storage unit Maximum fragment size for the data chunk size. Cohesity refers to this type of operation as whole image optimized duplication because an entire NetBackup image fragment is transferred.

Because larger chunks of data are transferred, fewer copy management requests occur and performance improves. Also, the storage device controls progress reporting. The storage device may report progress when system load is low rather than consume the resources that are better used for duplication. Or, the storage device may report progress at short intervals, updating the NetBackup user as frequently as NetBackup would for extent-based optimized duplication.

For whole image optimized duplication, the NetBackup bpstsinfo command output that shows the storage server capabilities shows the following two flags:

STS_SRVC_COPY_EXTENT
STS_SRVC_COPY_EXTENT_WHOLEIMAGE

The following is the syntax for the bpstsinfo command that shows the storage server capabilities:

bpstsinfo -storage_server host_name -stype vendor_string

More information about the bpstsinfo command is available.

See the NetBackup Commands Reference Guide:

The following are the requirements and limitations of optimized duplication with the same domain:

Optimized duplication requirements

The vendor must expose the off-host data movement capability in their plug-in.
Both the source and the destination disk pools must be the same OpenStorage vendor type.
One or more NetBackup media servers must connect to the source appliance and the destination appliance.

Optimized duplication limitations

If the optimized duplication fails, the job is not retried.
To configure NetBackup to do normal duplication if the optimized job fails, add the following entry to the bp.conf file on the NetBackup primary server:
RESUME_ORIG_DUP_ON_OPT_DUP_FAIL = TRUE
The copy operation uses the maximum fragment size of the source storage unit, not the setting for the destination storage unit. The optimized duplication copies the image fragments as is. For greater efficiency, the duplication does not resize and reshuffle the images into a different set of fragments on the destination storage unit.
To confirm the image copy, a media server must have connectivity to the destination appliance.
A storage unit group cannot be a destination for optimized duplication. The destination must be a storage unit that represents an OpenStorage appliance of the same type as the source appliance.

About OpenStorage optimized duplication within the same domain

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