NetBackup™ Backup Planning and Performance Tuning Guide
- NetBackup capacity planning
- Primary server configuration guidelines
- Media server configuration guidelines
- NetBackup hardware design and tuning considerations
- About NetBackup Media Server Deduplication (MSDP)
- MSDP tuning considerations
- MSDP sizing considerations
- Accelerator performance considerations
- Media configuration guidelines
- How to identify performance bottlenecks
- Best practices
- Best practices: NetBackup AdvancedDisk
- Best practices: NetBackup tape drive cleaning
- Best practices: Universal shares
- NetBackup for VMware sizing and best practices
- Best practices: Storage lifecycle policies (SLPs)
- Measuring Performance
- Table of NetBackup All Log Entries report
- Evaluating system components
- Tuning the NetBackup data transfer path
- NetBackup network performance in the data transfer path
- NetBackup server performance in the data transfer path
- About shared memory (number and size of data buffers)
- About the communication between NetBackup client and media server
- Effect of fragment size on NetBackup restores
- Other NetBackup restore performance issues
- About shared memory (number and size of data buffers)
- Tuning other NetBackup components
- How to improve NetBackup resource allocation
- How to improve FlashBackup performance
- Tuning disk I/O performance
Disk volumes with different characteristics
NetBackup allows multiple disk volumes to reside within a single disk pool. Load-balancing strategies are applied across all disk volumes within the disk pool during media and device selection (MDS). In other words, NetBackup assumes that all disk volumes within a disk pool are somewhat similar. This includes the areas of size and performance characteristics. While asymmetric configuration will not cause backups to fail, it is likely to result in unpredictable performance.
Example 1:
Assume a disk pool with one 800-GB disk volume and one 80-GB disk volume. When NetBackup selects a disk volume to be used for a backup job, this selection is essentially driven by the size (free space) of the disk volume. Because of the size difference in this case, the larger disk volume will initially receive a larger share of the backup traffic. While this is quite correct from the point of view of available space, it will limit the system-wide performance as the bulk of the I/O traffic will be directed to the one disk.
Example 2:
Assume a disk pool with two disk volumes of the same size. However, one volume has a transfer rate of 100 MB/sec and the other has a transfer rate of 25 MB/sec. Once again, load balancing will select a disk volume based on available free space. As a result both disk volumes will see the same amount of traffic but backups and restores will run much faster to one disk volume than the other.
Recommendation: All disk volumes within a NetBackup disk pool should be of similar size and should have similar performance characteristics. When dealing with disk volumes that have significantly different characteristics they should be grouped into multiple disk pools, each containing disk volumes with similar characteristics, rather than all being placed in one pool.