NetBackup™ Backup Planning and Performance Tuning Guide

Use multiplexing

Multiplexing writes multiple data streams from several clients to a single tape drive or several tape drives. Multiplexing can improve the backup performance of slow clients, multiple slow networks, and many small backups (such as incremental backups). Multiplexing reduces the time each job waits for a device to become available. It thereby makes the best use of the transfer rate of your storage devices.

Refer also to the NetBackup Administrator's Guide, Volume II for more information about using multiplexing.

Stripe a disk volume across drives.

A striped set of disks can pull data from all drives concurrently, to allow faster data transfers.

Maximize the use of your backup windows

You can configure all your incremental backups to happen at the same time every day. You can also stagger the execution of your full backups across multiple days. Large systems can be backed up over the weekend while smaller systems are spread over the week. You can start full backups earlier than the incremental backups. They might finish before the incremental backups and return all or most of your backup window to finish the incremental backups.

Convert large clients to SAN Clients

A SAN Client is a client that is backed up over a SAN connection to a media server rather than over a LAN. SAN Client technology is for large databases and application servers where large data files are rapidly read from disk and streamed across the SAN. SAN Client is not suitable for file servers where the disk read speed is relatively slow.

Use network bonding to join two or more network interfaces together to form a single interface

Network bonding simplifies network management and offers expanded network bandwidth and performance improvement over a single interface. It also improves the network redundancy: when one interface is down or unplugged, the other interfaces in the bonding can still work.

Avoid a concentration of servers on one network

If many large servers back up over the same network, convert some of them to media servers or attach them to private backup networks. Either approach decreases backup times and reduces network traffic for your other backups.

Use a dedicated media server for NetBackup operations

For a backup server, use a dedicated media server for backups only. Using a server that also runs several applications unrelated to backups can severely affect your performance and maintenance windows.

Consider the requirements of backing up your catalog

Remember that the NetBackup catalog needs to be backed up. To facilitate NetBackup catalog recovery, the primary server should have access to a disk storage server, a cloud server, or dedicated tape drive, either stand-alone or within a robotic library.

Level the backup load

To improve multi-stream backup performance for tape backups, you can use multiple drives and spread the load across them. Similarly, for multi-stream disk backups, you can configure multiple file systems on disks/LUNs. For best disk I/O performance, avoid multiple file systems from sharing the same disk or LUN.

Consider bandwidth limiting

Bandwidth limiting lets you restrict the network bandwidth that is consumed by one or more NetBackup clients on a network. The bandwidth setting appears under Host Properties > Primary Servers, Properties. The actual limiting occurs on the client side of the backup connection. This feature only restricts bandwidth during backups. Restores are unaffected.

When a backup starts, NetBackup reads the bandwidth limit configuration and then determines the appropriate bandwidth value and passes it to the client. As the number of active backups increases or decreases on a subnet, NetBackup dynamically adjusts the bandwidth limiting on that subnet. If additional backups are started, the NetBackup server instructs the other NetBackup clients that run on that subnet to decrease their bandwidth setting. Similarly, bandwidth per client is increased if the number of clients decreases. Changes to the bandwidth value occur on a periodic basis rather than as backups stop and start. This characteristic can reduce the number of bandwidth value changes.

Try throttling at different levels

NetBackup provides ways to throttle loads between servers, clients, policies, and devices. Note that these settings may interact with each other: compensating for one issue can cause another. The best approach is to use the defaults unless you anticipate or encounter an issue.