HP StorageWorks EBS with HP OpenView Storage Data Protector V5.1 Implementation Guide (October 2003)

Installation and Configuration
25EBS with HP OpenView Storage Data Protector v5.1 Implementation Guide
Source Disk and File Systems
In the past, tape performance was typically identified as a bottleneck. However,
tape performance has now surpassed may of the source systems available today.
Items to take into account when calculating desired throughput and performance
metrics are:
■ Source Hardware (disk subsystems)
■ Source Filesystem status
It is essential that the hardware you use for disk or online storage be able to
adequately provide data for the application online along with the backup
application and tape devices.
In environments deploying large tape subsystems using HP StorageWorks
ESL9000 Series Libraries and Ultrium 460 tape drives, disk subsystems become
an increasingly important performance component. One ESL9595 with 16
Ultrium 460 tape drives can easily maintain 500 MB/s of total system throughput.
In this scenario, it is recommended that your disk subsystems be able to maintain
a 2:1 ratio of disk-to-tape throughput. That would be approximately 1 GB/s of
disk I/O required to stream data to one ESL9595 tape library.
The impact of file systems on backup performance can be significant. Highly
fragmented systems only allow disk and tape subsystems to run at a fraction of
stated or desired performance. In some cases they can cause a device rated to
stream at 16 MB/s native to only perform at 3 MB/s.