what's the meaning of bypass

[public]

Hi all
when i looked up some documents about va7410 ,i can't understand some notes e.g:
"If there is any kind of failure with communication to a drive, the drive is bypassed"
what's the meaning of "bypass"

thanks

[John Kufrovich]

Bypass is a Fibre Channel term. In a loop environment, if a FC device goes offline, you would break the FC loop. With Bypass, the port can be disabled and normal loop communication can continue.

[Víctor Cespón]

Like other HP disk enclodures, the VA7410 uses FC-AL to connect the disks to the controller.

This is from VA7410 quickspecs:
Each drive is connected to each controller through a separate loop, enabling dual redundant FC loop connections, and eliminating the connection as a single point of failure.

If you look at a basic definition of FC-AL:
http://en.wikipedia.org/wiki/Fibre_Channel

Bypassed means the disk is left out of the loop. Since the frames from the controller to one disk must pass though all other disks, one disk can cause problems on the communication with other disks. In this case the controller can send the command to bypass it and leave it incommunicated.