EonStor DS S12/S16/S24 Series Hardware Manual
3.6.3
Configuration Rules
Following are the rules for connecting SAS interfaces across RAID and JBOD
enclosures:
Fault-tolerant links in a dual-controller combinations: Corresponding to SAS
drives’
dual-ported
interface, two physical links are available from each disk
drive, routed across the backplane board, each through a SAS expander, and
then interfaced through a 4x wide external SAS port.
With data paths through separate SAS domains, access to disk drives can be
continued in the event of a cable link or SAS JBOD controller failure.
Fault-tolerant Links to SAS disk Drives
SAS expansion cables will be available with Infortrend’s JBODs. Note that if many
JBODs are connected, a longer SAS external cable (e.g., a 120cm cable) may be
necessary for connecting a JBOD from the opposite direction offering high
redundancy.
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.
Each expander controller on the SAS JBOD 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 controls
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