The concept of synthesizing full backups from previous full and new incremental backups had been in the industry for a while. The idea is to run incremental backups on client system so that its CPU and memory resources are used minimally. In addition, as the full data set is not moved over network, it is a great way to save network bandwidth.
There are a few problems with these traditional synthetic methods. The new image is synthesized by reading previous full and newer incremental backups from secondary storage (in NetBackup terms, from the storage units) and creating a new backup stream that gets written back to storage. The new backup stream is the synthetic image. Traditional synthetic backup simply moved the processing overhead to backup server. Although this is great from client’s perspective, implementing synthetic backups for hundreds of clients would require more resources on backup servers. Plus, there is significant I/O at storage as these backup servers are constantly reading old images and writing new synthetic ones, hence the storage could become the bottle neck in meeting the SLA.
NetBackup features Optimized Synthetic Backups, a patented technology that takes the art and science of synthesizing backups to a cut above. This feature is available when using NetBackup’s deduplication storage pools like NetBackup Deduplication Option, Media Server Deduplication Option and NetBackup appliances.
What is Optimized Synthetics?
We know that backups are stored in NetBackup deduplication pools in deduplicated format. You never store the same piece of data segment more than once. These segments are identified using unique fingerprints. A backup is nothing but a collection of fingerprints pointing to these segments one or more times. When you ask NetBackup to create a synthetic backup, it gets created by generating a new pointer where fingerprints from recent full backup and newer incremental backups are accommodated such that the new collection will only have finger prints for those data segments which would have been present if the full backup was directly run on the client. This operation happens on deduplication storage. The media server is not reading or writing any of these data segments. Furthermore, even the storage server isn’t moving any of segments around. The result is a synthetic backup that was created without using the resources from client, backup server and network! It enables super fast full backups without making storage I/O as a bottle neck for your SLA!
How to setup Optimized Synthetic Backups?
Setting up Optimized Synthetic Backup has two steps
- Configuring the NetBackup Deduplication Pool to support Optimized Synthetics. Please refer to Symantec NetBackup 7.1 Deduplication Guide for details on setting up Optimized Synthetic Backups.
- Configuring backup policies with Synthetic backup schedule, this is documented in NetBackup System Administrator's Guide. Note that this part is the same whether you want to configure a traditional synthetic backup or optimized synthetic backup.
Alternately, please refer to this TechNote for the full set of instructions: