System Connection; General Considerations On Making Connections - Infortrend S12 Series Hardware Manual

System Connection

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This chapter outlines the general configuration rules you should follow when cabling
a storage system and introduces basic information about topologies. You can use
these topologies or refer to them as a guide for developing your own unique
topologies. A complete description of the power-on and power-off procedures is also
given in this chapter.

General Considerations on Making Connections

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When selecting the number of hard drives to be included in a logical drive, the host
channel bandwidth and the mechanical performance of individual disk drives should
be considered.
It is a good practice to calculate performance against the host port bandwidth when
designing an application topology. As an example, if eight members are included in a
logical drive and this logical drive is associated with a host ID (LUN mapping), the
combined performance of this logical drive should approximate the channel
bandwidth. If, for example, two 6-drive logical arrays are associated with two IDs
residing on a single host channel, there may be a trade-off with performance.
If your system comes with dual controllers for a total of 8 host ports, it is
recommended that you obtain more disk drives by attaching a JBOD so that you can
create 4 or more 6-member logical drives. These 4 logical drives leverage the
bandwidth of all 8 host ports.
There are other considerations:

For example, a spare drive carries no data stripes and will not contribute to
disk-level performance. Refer to the documentation for your hard drives for
performance data.

When cabling, follow all the specifications. Pay attention to signal quality and
avoid electronic noise from adjacent interfaces, e.g., do not lay power cords
on optical cables.

The disk drives in the same logical array should have the same capacity, but it
is preferred that all the drives within a chassis have the same capacity.

Disk drives in the same logical drive should have the same capacity, but it is
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