Infortrend DS 3012U, Руководство по оборудованию

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2-39 EonStor DS 3000 Series Hardware Manual
• Fault-tolerant links to SAS disk drives
- The SAS expansion cables are bundled with the expansion systems. Take note that if there are
many expansion systems connected, a longer SAS external cable, approximately measured
120 cm, may be needed to connect an expansion system from the opposite direction for a
higher redundancy.
- One expansion link connects the expansion system from a SAN storage system with HBA/
RAID card to the nearest expansion system, then to the most distant expansion system.
Another expansion link connects to the most distant expansion system, from the opposite
direction to the first expansion system from the SAN storage system.
- Each expander controller on the SAS expansion system controls a SAS domain that connects
to one of the alternative interfaces of the disk drives in the enclosure. For example, one
expander unit controls Domain A while the other expander controls Domain B. In a fault-
tolerant topology, the SAS external links always connect to the SAS ports of the same SAS
domain.
- Identify the SAS domains by the location of the expanders: the upper controller is controller A,
the lower one is controller B.
- On a SAN storage system, each controller is considered as managing a separate SAS domain.
With the help of the port selector mechanism on the MUX boards, the idea of SAS domain
applies even when SATA drives are used in a dual-controller expansion system.
Connecting expansion systems
• Connecting dual-controller expansions
or the last expansion