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3.1
Introduction
This chapter outlines the general configuration rules users should follow when
cabling a storage system and provides basic information about topologies. Users can
either use these topologies or reference them for developing unique topologies. A
complete description of the power-on and power-off procedures is also provided in
this chapter.
3.2
General Considerations for Connections
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.
We recommend calculating 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, performance may be reduced.
If your system comes with dual controllers for a total of 8 host ports, we recommend
obtaining additional disk drives by attaching a JBOD to enable the creation of at least
four 6-member logical drives. These four logical drives leverage the bandwidth of all
eight host ports.
Some additional considerations are outlined as follows:
A spare drive carries no data stripes and will not contribute to disk-level
performance. Refer to the relevant hard drive documentation for performance
data.
Disk drives in the same logical array should have the same capacity. Ideally, all
the drives within a chassis should have the same capacity.
Disk drives in the same logical drive should have the same capacity. Ideally, all
the disk drives within a chassis should have the same capacity. Tiered storage
configuration is supported (e.g., 150GB SAS drives in the RAID enclosure and
750GB SATA drives in JBODs). However, SAS and SATA drives should not both
be included in a logical drive.
A spare drive should have a minimum capacity that equals the largest drive it is
expected to replace. If the capacity of the spare is less than the capacity of the
drive it is expected to replace, the controller will not proceed with the failed drive
rebuild.
When cabling, follow all specifications. Pay attention to signal quality and avoid
electronic noise from adjacent interfaces (e.g., do not place power cords on
optical cables).
When rack-mounted, leave enough slack in the cables to prevent bending to a
diameter of less than 76 mm (3 inches).
Route the cables away from areas with a high likelihood for damage (e.g., from
foot traffic or fan exhaust).
Do not over-tighten or bend the cables.
ASR-5300I Series Hardware User Manual
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