Auxiliary Copy Overview
The Auxiliary Copy operation creates additional standby copies of data. These standby copies are referred to as secondary copies. You can use different media and different libraries for the primary and secondary copies. For the auxiliary copy operations, jobs with valid data are copied sequentially from the primary copy to the secondary copy. Valid data is defined as the data from a data protection job that has not failed or has not been killed.
If the primary copy becomes inoperative due to a storage media failure or a library or network malfunction, you can promote a secondary copy to become the primary copy. Promoting a secondary copy allows you to continue operations as before and make repairs without interrupting backup and restore operations.
You can create three types of secondary copies:
- Synchronous secondary copy
A Synchronous secondary copy automatically includes all valid data from a source copy. For more information, see Secondary Copy (Synchronous Copy).
- Selective secondary copy
A Selective secondary copy automatically includes valid Full or Synthetic Full backup data based on specified criteria. A Selective copy also has a manual job selection option that enables the user to select any type of job, including non-full backups. For more information, see Secondary Copy (Selective Copy).
- IntelliSnap Backup copy
An IntelliSnap Backup copy is used to manage the retention of snapshots started by a data protection job. The IntelliSnap backup copy also holds the archived index data if the snapshot is granularly indexed. For more information Backup Copy for IntelliSnap Backup.
Auxiliary copy operation key features
The data streams on the primary copy are copied to a secondary copy. To optimally use the streaming feature you can do the following:
- Set the number of streams for an auxiliary copy operation
- Enable combine stream
- Combine streams using data multiplexing
- Configure stream randomization
- Configure dynamic stream allocation
The dynamic stream allocation is enabled by default in the current software version. However, if you have upgraded to the current software version , you can enable it as described in Configuring Dynamic Stream Allocation.
For more information, see Streams Overview.
Data compression options are provided for data secured by data protection operations. Compression reduces the quantity of data sent to the storage, often doubling the effective capacity of the media (depending on the nature of the data). If the data is later restored, the system automatically decompresses the data and restores it to its original state.
Software compression is available for all storage media. If you have enabled the software compression for a subclient, then backup data will not get uncompressed during the auxiliary copy operation.
The hardware compression is transparent. The hardware compressed data is uncompressed by the tape device on read, and recompressed during tape write.
For more information, see Data Compression.
Data Encryption encrypts the data both for transmission over non secure networks and for storage on media. Encryption at the Auxiliary copy level encrypts the data during the auxiliary copy operation.
For more information, see Data Encryption - Overview.
Deduplication provides an efficient method to transmit and store data by identifying and eliminating duplicate blocks of data during backups. An Auxiliary copy job uses DASH (Deduplication Accelerate Streaming Hash) copy, which is an option for a deduplication-enabled storage policy copy, to send only unique data to that copy. DASH copy uses network bandwidth efficiently and minimizes the use of storage resources.
For more information, see Deduplication Overview.
The process flow for Auxiliary Copy involves the following tasks in the order listed: