Galaxy A16F-R2431 Installation and Hardware Reference Manual
3-4
Topology and
Configuration Considerations
When selecting the number of hard drives that will be configured into a
logical configuration, the mechanical performance of the hard disks
should be considered. As shown below, if eight (8) members are
included in a logical drive, this logical drive should be associated with a
host ID, and accessed through a host channel making efficient use of
the channel bandwidth.
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 that came with your hard drives for performance
data.
Figure 3-1: Drive Mechanical Speed and Logical Drive Speed
When cabling, follow all Fibre Channel specifications. Pay attention to
signal quality and avoid electronic noise from adjacent interfaces.
The disk drives in the same logical array should have the same capacity,
but it is preferred that all the drives within the subsystem have the same
capacity.
A spare drive (Local, Global, or Enclosure spare) should have a
capacity equal or larger than the largest drive that it is expected to
replace. If the capacity of the spare is smaller than the capacity of the
faulty drive it is expected to replace, then the system firmware will halt
the logical drive rebuild process.
