HP B6960-90078 manual Configuring Backups and Restores, Device Streaming, Block Size

Further Information

Performance Considerations

•Load Balancing: This is where Data Protector dynamically determines which filesystem should be backed up to which device. Normally, it is best to enable this feature. This is especially true when a large number of filesystems in a dynamic environment are being backed up.

Configuring Backups and Restores

Any given infrastructure must be used efficiently in order to maximize performance. Data Protector offers high flexibility in order to adapt to the environment.

Device Streaming

To maximize a device’s performance, it must be kept streaming. A device is streaming if it can feed enough data to the medium to keep it moving forward continuously. Otherwise, the tape has to be stopped, the device waits for some more data, reverses the tape a little and resumes to write to the tape, and so on. In other words, if the data rate written to the tape is less or equal the data rate which can be delivered to the device by the computer system, then the device is streaming. In network-focused backup infrastructures, this deserves attention.

Backups can be setup so that the data from several disk agents is sent to one Media Agent, which sends the data to the device.

Block Size

The device hardware processes data it receives using a device type specific block size. Data Protector allows to adjust the size of the block it sends to the device. The default value is 64kB.

Increasing the block size can improve the performance. Changing the block size should be done before formatting tapes. For example, a tape written with the default block size cannot be appended to a tape using a different block size.

Software Compression

Software compression is done by the client CPU when reading the data from the disk. This reduces the data which gets send over the network, but it requires significant CPU resources from the client.

A-10 Appendix A