Compaq ProLiant 1000 I/O Performance Tuning of Compaq Servers - Page 12

Fibre Channel

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I/O Performance Tuning of Compaq Servers 12 Table 3. Smart-2 Controller Family Model Smart-2SL Controller Smart-2DH Controller Smart-2/P Controller Smart-2/E Controller Smart Array 3100 ES Smart Array 3200 Number of SCSI Channels (Busses) 2 2 2 2 3 2 Maximum Number of Spindles 30 30 30 30 45 30 Table 4. ProLiant Storage Systems Model ProLiant Storage System U1 ProLiant Storage System U2 ProLiant Storage System ProLiant Storage System UE Number of SCSI Channels Maximum Number of (Busses) Drives 1 7 2 8 1 7 2 12-1" or 8-1.6" SCSI Revision Supported Wide-Ultra SCSI-3 Wide-Ultra SCSI-3 Fast-Wide SCSI-2 Wide-Ultra SCSI-3 The SMART-2 family of controllers and the ProLiant Storage System boxes provide an integrated storage array solution. The various topologies these combinations present must be load balanced with the awareness of where the busses and their combined load are. Details of the Smart-2 family of array controllers and the ProLiant Storage System boxes are presented in the two tables above. On controllers with two independent busses, making certain that the I/O load is evenly distributed can provide higher sustained throughput from the SCSI interface. When drives of similar performance and load are used, balancing the SCSI busses is as simple as dividing the number of drives on each bus evenly. However, drives should not be divided evenly if dividing the drives between the SCSI busses will require placing a higher I/O load on one of the two busses. SCSI Bandwidth & Saturation Because disk requests can be combinations of reads or writes, random or sequential, and small or large; SCSI throughput is the most application-dependent I/O factor. In some server mixes the bandwidth limit will never be reached. If you are doing random data retrieval, your drives will spend more time seeking the data, and the data is so small that the transfer will be off of the SCSI bus before the next read is completed by the drive. When small, random reads are the norm, you can have many more devices on your SCSI bus before you reach saturation. However, large block data transfer environments, such as video editing, will cause the drives to do fewer seeks and retrieve large, contiguous streams of data. In this case, a Wide-Ultra SCSI-3 bus can be saturated by as few as 4 drives. Once the SCSI bus has become saturated adding more drives can actually degrade performance. Be aware of the load placed on your server and maximize SCSI bandwidth accordingly. Fibre Channel Fibre Channel (FC) is the next generation in storage technology. FC combines a high-speed connection between server and storage with flexibility and expandability. This high-speed link is ECG044.0399

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I/O Performance Tuning of Compaq Servers
12
ECG044.0399
Table 3.
Smart-2 Controller Family
Model
Number of SCSI Channels (Busses)
Maximum Number of Spindles
Smart-2SL Controller
2
30
Smart-2DH Controller
2
30
Smart-2/P Controller
2
30
Smart-2/E Controller
2
30
Smart Array 3100 ES
3
45
Smart Array 3200
2
30
Table 4.
ProLiant Storage Systems
Model
Number of SCSI Channels
(Busses)
Maximum Number of
Drives
SCSI Revision Supported
ProLiant Storage System U1
1
7
Wide-Ultra SCSI-3
ProLiant Storage System U2
2
8
Wide-Ultra SCSI-3
ProLiant Storage System
1
7
Fast-Wide SCSI-2
ProLiant Storage System UE
2
12-1" or 8-1.6"
Wide-Ultra SCSI-3
The SMART-2 family of controllers and the ProLiant Storage System boxes provide an
integrated storage array solution. The various topologies these combinations present must be load
balanced with the awareness of where the busses and their combined load are. Details of the
Smart-2 family of array controllers and the ProLiant Storage System boxes are presented in the
two tables above.
On controllers with two independent busses, making certain that the I/O load is evenly distributed
can provide higher sustained throughput from the SCSI interface. When drives of similar
performance and load are used, balancing the SCSI busses is as simple as dividing the number of
drives on each bus evenly. However, drives should not be divided evenly if dividing the drives
between the SCSI busses will require placing a higher I/O load on one of the two busses.
SCSI Bandwidth & Saturation
Because disk requests can be combinations of reads or writes, random or sequential, and small or
large; SCSI throughput is the most application-dependent I/O factor. In some server mixes the
bandwidth limit will never be reached. If you are doing random data retrieval, your drives will
spend more time seeking the data, and the data is so small that the transfer will be off of the SCSI
bus before the next read is completed by the drive. When small, random reads are the norm, you
can have many more devices on your SCSI bus before you reach saturation.
However, large block data transfer environments, such as video editing, will cause the drives to
do fewer seeks and retrieve large, contiguous streams of data. In this case, a Wide-Ultra SCSI-3
bus can be saturated by as few as 4 drives. Once the SCSI bus has become saturated adding more
drives can actually degrade performance.
Be aware of the load placed on your server and maximize SCSI bandwidth accordingly.
Fibre Channel
Fibre Channel (FC) is the next generation in storage technology. FC combines a high-speed
connection between server and storage with flexibility and expandability. This high-speed link is