Galaxy GHDXS2-1430R-16F4D Installation and Hardware Reference Manual
3-12
3.4.3 Drive-side
Expansion
Configuration Rules:
Dual-port Configuration Feature:
Following are the rules for connecting SAS interfaces across RAID and
JBOD enclosures:
1.
Corresponding to SAS drives’
dual-ported
interface, two (2) physical
links are available from each disk drive, routed across the backplane
board, and then interfaced each through a 4x wide external SAS port.
2.
SAS expansion cables will be available with Rorke’s JBODs. Note that
if many JBODs are connected, a longer SAS external cable may be
necessary to connect a JBOD from the other direction offering path
redundancy even when one of the JBODs fails.
One expansion link connects JBODs from RAID to the nearest JBOD,
and then to the farthest JBOD. Another expansion link connects to the
farthest JBOD from the opposite direction and then to the nearest
JBOD.
3.
Each expander controller controls a “
SAS Domain
” that connects one
of the alternative interfaces on all of the disk drives in the enclosure.
For example, one expander unit controls Domain A and the other
Domain B. In a fault-tolerant topology, the SAS ports always connect to
the SAS ports on the same SAS Domain. The Domains can be
identified by the expanders’ locations, i.e., upper controller slot
(Controller A) or the lower controller slot (Controller B).
Figure 3-7: SAS Domains