ATTO Technology 2500C Manual De Usuario

31

 

ATTO Technology Inc. iPBridge Installation and Operation Manual

If the host is not getting the performance it should, 
check the following items. 

1

Verify that the devices are running at their 
highest possible SCSI speed. Refer to 

Mixing SE and LVD devices on the same SCSI 
bus forces the speed of the bus to SE, thus 
slowing faster LVD devices. The iPBridge 
cannot accelerate an already slow device. 
Refer to 

 on page iii of the Appendix.

2

Verify that the proper terminator is being used. 
An SE terminator forces the SCSI bus to SE 
speeds.

1

Verify that the SCSI port configuration is set to 
the highest speed using the ATTO ExpressNAV 
interface or CLI. Refer to 

 on page 47.

The iPBridge SCSI port speed, wide 
negotiation, and sync negotiation settings all 
affect the speed of the port. By default, these 
settings are set for optimal speed.

2

Verify that the SCSI devices are equally 
distributed between the SCSI ports. Refer to 

 on page 33. 

Optimal performance is seen when only two 
high-speed SCSI devices are connected to 
each SCSI port.

1

Verify that the data ports are set to auto 
negotiate or forced to 1000 Mbs. Refer to 

2

Verify that the MTU size is set to optimal setting 
for the LAN/WAN environment. 
Refer to 

23. The current optimized frame size for the 
iPBridge is 9k. Smaller frame sizes cause a 
decrease in performance.

3

Verify that the iPBridge 

TraceLog

 feature is 

disabled. Tracelog tracks certain events that 
occur in the iPBridge. With this log enabled, 
performance suffers. 
Refer to 

1

Verify that the MTU size is set to optimal setting 
for the LAN/WAN environment. Refer to 

9k frame size is the current optimized frame 
size for the iPBridge. smaller frame sizes cause 
a decrease in performance. Many switch and 
router vendors do not support the larger frame 
size of 9k or 16k. 

2

Verify that each associated port in the IP SAN 
is configured for 1000Mbs.
IP SAN traffic should be segmented so that it 
does not interfere with the main LAN network 
traffic.For better performance, the IP SAN 
should be on its own set of hardware.

3

Verify that packets are not being dropped along 
the LAN/WAN. Many utilities track packet 
activity and switch statistics.

Ethernet Storage Adapters generally outperform 
accelerated NICs and un-accelerated NICs by 
offloading most of the processing from the host.
An accelerated NIC provides some offloading, but still 
requires a host OS iSCSI driver, making the host spend 
more CPU cycles.
An un-accelerated NIC does not offload anything so 
the CPU must do much of the processing.
To check the Ethernet host adapter or NIC

1

Verify that the adapter or NIC is sent to auto-
negotiate or forced to 1000 Mbs.

2

Set the MTU size to the largest MTU size 
supported in the LAN/WAN. Refer to 

9k frame size is the current optimized frame 
size for the iPBridge. smaller frame sizes cause 
a decrease in performance. Many switch and 
router vendors do not support the larger frame 
size of 9k or 16k. Set the maximum transfer 
size to the most efficient size for the intended 
target(s). For many tape drives, 64k is the 
optimal setting.

Some applications can be configured to change 
transfer sizes. Configure the application for the 
optimal size for the particular SCSI device(s) 
connected to the iPBridge.