HP ProLiant DL585 G5 - Manual (Page 14)

Test analysis summary
Figure 5 summarizes the optimal numbers of users supported by the HP ProLiant DL585 G5 server.
Figure 5. Optimal numbers of users supported in the 64-bit test harness
HP characterized the scalability of the HP ProLiant DL585 G5 server through the numbers of users
supported when CPU utilization reached 80%.
Recommendations
Since x64 platforms allow you to better utilize memory and multi-core processors, the bottleneck you
are most likely to encounter 6 is associated with the disk subsystem. While a detailed analysis of disk
I/O performance is beyond the scope of this white paper, the following observations are offered to
help you improve disk performance:
•
Utilize battery-backed write cache (see Using BBWC ).
• Since built-in storage is often insufficient to support a large number of users in an HP SBC
environment, consider deploying additional RAID arrays/SAN support.
Note also that when a SCSI RAID array is used to host user profiles and page files, the number of
spindles deployed has a significant impact on the response times associated with file access.
• When the pressure on the disk I/O subsystem is high, one option for improving disk access times is
to add RAM to lower the pressure on memory.
As the number of sessions increases, disk activity and the pressure on the disk I/O subsystem also
increase. If file I/O activity is high, the probability that requests will find the desired data in
memory decreases, thus negatively affecting file access times.
To help avoid a disk I/O bottleneck, Microsoft recommends using the Windows performance
monitoring tool, Perfmon, to check the following metrics 7 :
• %Idle time – Idle times for logical and physical drives should average at least 50%
• Average Disk Seconds/Read and Average Disk Seconds/Write – The average time taken to
complete a read or write should average less than 25 milliseconds, with peaks less than 50
milliseconds
If the above conditions specified by Microsoft cannot be met, a disk I/O bottleneck is likely.
6 For further information, refer to the HP white paper , “Scalability and performance of HP ProLiant servers on 64-bit Microsoft
Windows Server 2003 in an HP SBC environment.”
7 For further information, visit the Microsoft website ; click the Start download link.
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