16
Cabling for
Performance
Generally speaking, performance is enhanced by maximizing bandwidth, which is the
ability to process more I/O across more channels. Therefore, a configuration that
maximizes the number of host channels and the number of drive channels available to
process I/O will maximize performance. Of course, faster processing speeds also
maximize performance.
The DE6900 drive tray supports drive-side trunking. You can use drive-side trunking
with the appropriate cabling configuration to, potentially, double the bandwidth
available by making two drive channels simultaneously available to the same drive
tray or loop.
In addition to planning a topology that provides maximum performance, choose a
RAID level that suits the planned applications. For information on RAID levels, refer
to the topics under Concepts or to the corresponding PDF document on the
SANtricity ES Storage Manager Installation DVD.
Fibre Channel
Drive-Side Trunking
Drive trays that support drive-side trunking can be connected to a controller tray
through a cabling pattern that doubles the bandwidth available to the drive trays.
Trunking is possible only with drive trays that have Fibre Channel switch on a chip
(SoC) loop-switch technology.
Drive-side trunking is an important feature for high-density drive trays because it
enables a configuration with fewer drive trays connected to a controller tray to take
advantage of the maximum bandwidth available for drive connections. For example, a
storage array consisting of four DE6900 drive trays connected using drive-side
trunking to a CE7900 controller tray with two controllers can take advantage of all of
the available bandwidth on the controller tray. Without drive-side trunking, the four
drive trays can only use half of the available bandwidth.
Each environmental services module (ESM) on a drive tray that is capable of
drive-side trunking has four ports. In the previous example, two ports on each ESM
would connect to each of two ports of a dual-ported drive channel on the controller
tray. A new drive tray could be added to the example configuration by connecting two
ports on each ESM of the new drive tray to the two available ports on each ESM of
one of the existing drive trays. The new drive tray would then share Fibre Channel
loops with the drive tray to which it is connected.
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