Infortrend S12 Series Hardware Manual page 110

EonStor / EonStor DS S12/S16/S24 Series
offering high redundancy.

One expansion link connects JBODs from RAID to the nearest JBOD, and
then to the fa rthest 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
controls Domain B. In a fault-tolerant topology, the SAS external links always
connect to the SAS ports on the same SAS Domain.

The SAS Domains can be identified by the expanders' locations, i.e., upper
controlle r slot (Controller A/
B/Slot B).

On the RAID system, each RAID controller can be considered as managing
a s eparate SAS Domain. With the help of the port s
the MUX boards, the idea of
are used in a dual-controller JBOD.
Slot A ) or the lowe r contro
SAS Dom ain applie s even when SATA
110
A, and the other
ller slot (Cont roller
elector mec hanism on
drives