Apple Xsan 2 - Manual (Page 53)

Chapter 3 Plan a SAN 53
Check cables
One faulty cable in a fabric can slow the entire network. Check all cables to make sure
they’re capable of full transmission speed. Use your switch management software to
isolate the faulty cable by checking the performance of specific connections.
Use qualified transceivers
Check with the manufacturers of the devices you’re connecting to your fabric to be
sure that the transceivers (GBICs) you’re using are qualified for use with their devices.
With some Fibre Channel switches, you should use identical transceivers (same
manufacturer and model number) on both ends of each cable. Mismatched optical
transceivers (even if they are separately qualified for use with your devices) can cause
Fibre Channel communication errors and degrade SAN performance.
With Cisco Fibre Channel switches, you should use a Cisco transceiver on the end of a
cable that plugs into the switch, but use another qualified transceiver at the other end
of the cable.
For Fibre Channel hardware compatibility information, see the AppleCare Support
article at support.apple.com/kb/HT1769.
Check Fibre Channel switch port configuration
The Request for State Change Notifications (RSCN) that is generated when a client on
the SAN restarts can cause dropped frames in video streams to other clients.
To avoid interrupting SAN traffic to other clients if one client restarts, check your Fibre
Channel switch documentation to see if you can configure the switch to suppress
RSCNs on initiator ports. (For example, on Qlogic switches this feature is called I/O
StreamGuard.)
Connect devices to specific blades
If your Fibre Channel switch is based on a blade architecture, you might be able to
improve performance by:
Connecting pairs of devices that routinely exchange large volumes of data to the Â
same blade in the switch
Distributing loads across multiple blades instead of concentrating all of the load on
Â
one or two blades
Configure RAID systems
Follow these guidelines when you set up your RAID systems for use as Xsan LUNs.
Install the latest firmware
To get the best performance and reliability from your RAID systems, install the
latest firmware.