138
One CDE3994
Controller-Drive
Tray or CDE3992
Controller-Drive
Tray and Multiple
Types of Drive Trays
If you are connecting more than one type of drive tray to the CDE3994
controller-drive tray, be sure to read "Connecting to Drive Trays That Support Loop
Switch Technology" on page 22.
Follow these guidelines for connecting multiple types of drive trays to maximize
performance and accessibility. The first device on the drive channel is distinguished
by the fact that the left ESM of the first device is connected directly to controller A of
the controller tray or controller-drive tray. Because an optimal redundant cabling
topology requires that the redundant drive channel be connected in the opposite order,
this same device will be the last in the drive channel when connected to controller B.
The following figure provides an example of how flexible the cabling can be when
you use a CDE3994 controller-drive tray as the controller. The firmware is able to
detect, and correctly handle, combinations of drive trays with both side-by-side ESMs
and inverted ESMs. This feature allows you to easily add new drive trays to your
storage environment, while continuing to take advantage of pre-existing drive trays
that you own.
If your storage array includes AT2655 drive trays, it is still advisable to connect the
AT2655 drive trays so that they are the last devices on the drive channel (farthest from
controller A).
NOTE When you mix different types of drive trays, you must consider the total
number of drives that are available in the final configuration of the storage array. For
example, if you mix FC4600 drive trays with FC2610 drive trays, the total number of
drives might be more than the maximum number that each drive channel can support.
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