HP Data Protector Software Performance White Paper

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Figure 44 shows how backup server disks were reconfigured for testing. One SAS array was
created based on four internal 72 GB 15K SAS disks and all space was allocated for a single
logical drive in RAID 1+0 mode.
Figure 44. Smart array configuration of backup server – one logical drive in RAID 1+0 mode and 4 SAS disks
As shown in Table 11, the backup performance of typical files in test 1 (125.42 MB/s) was
considerably improved with asynchronous reading enabled (163.09 MB/s). The backup
performance of small files in test 2 (9.23 MB/s) was slightly degraded with asynchronous
reading enabled (8.42 MB/s).
Table 11. Synchronous and asynchronous read test
Test Performance (MB/s)
Async Read OFF
Performance (MB/s)
Async Read ON
Async Read ON
Effect
1. Typical files 125.42 163.09 + 30.04%
2. Small files 9.23 8.42 − 8.78%
Note: The backup performance could decrease if asynchronously reading a large number of
small files (file size less than 100 KB).
Note: Non-asynchronous reading usually results in a disk queue length less than 1. On the
other hand, asynchronous reading increases the disk queue length and could impact the
performance of an application if the same physical disks are accessed.