HP ProLiant 4500 Disk Subsystem Performance and Scalability - Page 23

Table 9, Like Capacity Scaling Advantages and Disadvantages

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ECG025.0997 WHITE PAPER (cont.) ... Like Capacity Scaling (RAID 5 - 1 Controller) 14,000,000 12,000,000 10,000,000 8,000,000 28% 11+1 x 2GB 5+1 x 4GB 2+1 x 9GB Server Throughput (Bytes/sec) 6,000,000 4,000,000 2,000,000 0 4 8 16 20 24 28 32 36 40 44 48 52 56 57 Number of Clients Figure 12: Like Capacity Scaling in a RAID 5 Environment. Table 9 lists the advantages and disadvantages of like capacity scaling. Review and consider these items before making any decisions on what is right for your environment. Table 9: Like Capacity Scaling Advantages and Disadvantages Advantages Disadvantages Eliminates bottlenecks because you minimize seek time. Purchasing more disks for the same amount of disk space could be viewed as a more expensive solution for your environment. For example, purchasing four 2GB drives instead of two 4GB drives. Increases I/O concurrency because you have more drives processing disk requests. By not buying the latest technology, you might be missing new features that increase performance. For example, the latency time for a new 9GB disk might be faster than an older 4GB disk. Higher number of drives, improves the performance (more concurrency). Using smaller size drives limits your maximum capacity per controller. For example, the Compaq SMART-2 Array Controller supports up to 14 drives. By using fourteen 2GB drives, your data capacity equals 28GB. By using fourteen 4GB drives, your data increase to 56GB. By adding more drives to your system you have more disks to manage, thus increasing the probably of disk failure. 23

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W
HITE
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APER
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Like Capacity Scaling (RAID 5 - 1 Controller)
0
2,000,000
4,000,000
6,000,000
8,000,000
10,000,000
12,000,000
14,000,000
4
8
16
20
24
28
32
36
40
44
48
52
56
57
Number of Clients
Server Throughput (Bytes/sec)
11+1 x 2GB
5+1 x 4GB
2+1 x 9GB
28%
Figure 12: Like Capacity Scaling in a RAID 5 Environment.
Table 9 lists the advantages and disadvantages of like capacity scaling.
Review and
consider these items before making any decisions on what is right for your environment.
Table 9:
Like Capacity Scaling Advantages and Disadvantages
Advantages
Disadvantages
Eliminates bottlenecks because you
minimize seek time.
Purchasing more disks for the same amount of disk space could be
viewed as a more expensive solution for your environment.
For
example, purchasing four 2GB drives instead of two 4GB drives.
Increases I/O concurrency because you
have more drives processing disk requests.
By not buying the latest technology, you might be missing new
features that increase performance.
For example, the latency time
for a new 9GB disk might be faster than an older 4GB disk.
Higher number of drives, improves the
performance (more concurrency).
Using smaller size drives limits your maximum capacity per
controller.
For example, the Compaq SMART-2 Array Controller
supports up to 14 drives.
By using fourteen 2GB drives, your data
capacity equals 28GB.
By using fourteen 4GB drives, your data
increase to 56GB.
By adding more drives to your system you have more disks to
manage, thus increasing the probably of disk failure.