HP Data Protector Software Performance White Paper

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Disk write performance
The disk write performance was determined with L&TT for HP-UX and with the HPCreateData
utility for Windows.
Note: The performance data of parallel writes is determined by the data volume divided by the
time of the slowest write process. This approach simulates a backup application that does not
finish until the last byte is written.
Figure 28 demonstrates that single writes of typical files (one stream to one disk volume)
already perform well compared to multiple writes (five streams to five disk volumes). With
Windows, single writes of small files (4 – 16 KB) are very slow because the NTFS file system
overhead is much higher than with HP-UX VxFS.
Figure 28. Results of disk write tests
For Windows, parallel writes (five streams to five disk volumes) of small files failed due to
problems with an overflow of the Windows system paged pool. This cannot be solved without
tuning the Windows kernel, which is beyond the scope of this white paper.
Note: For Windows, it is recommended that file systems with millions of small files are only
restored in a single stream.
Disk Write Performance
Typical and Millions of Small Files
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20
51
193
165
134
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50.00
100.00
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250.00
Typical
Single
Windows
Typical
Parallel
Windows
Typical
Single HP-
UX
Typical
Parallel
HP-UX
Small
Single
Windows
Small
Single HP-
UX
MB/s