HP B6960-96035 manual Full and incremental backups, Disk image versus filesystem backups

Full and incremental backups

A basic approach to improve performance is to reduce the amount of data to back up. Carefully plan your full and incremental backups. Note that you may not need to perform all the full backups of all the client systems at the same time.

If you back up to disk, you can use advanced backup strategies such as synthetic backup and disk staging.

Disk image versus filesystem backups

It used to be more efficient to back up disk images (raw volumes) rather than filesystems. This is still true in some cases, such as heavily-loaded systems or disks containing large numbers of small files. The general recommendation is to use filesystem backups.

Object distribution to media

The following are examples of object/media backup configurations provided by Data Protector:

•One object (disk) goes to one medium

The advantage is a known fixed relationship between an object and a medium where the object resides. This can be of benefit for the restore process, since only one medium needs to be accessed.

The disadvantage in a network backup configuration is the likely performance limitation due to the network, causing the device not to stream.

•Many objects go to a few media, each medium has data from several objects, one object goes to one device

The advantage here is the flexibility of datastreams at backup time, helping to optimize performance, especially in a network configuration.

The strategy is based on the assumption that the devices receive enough data to be able to stream, since each device receives data from several sources concurrently.

The disadvantage is that data (from other objects) has to be skipped during the restore of a single object. Additionally, there is no precise prediction as to which medium will receive data from which object.

For more information on device streaming and backup concurrency, see “Device streaming and concurrency” on page 156.

Concepts guide 71