Dot Hill Systems SANnet II 200, Installation, Operation And Service Manual

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4-20 SANnet II 200 SCSI Array Installation, Operation, and Service Manual • June 2005
Note –
When connecting to Ultra3 host adapters, all SCSI cables must be Ultra3-
qualified.
Note –
If you connect two hosts to the same channel on a RAID array, you do not
need to change the scsi-initiator-id of one host adapter.
4.10 Cabling to Expansion Units
Designed for a fully redundant configuration, a standard RAID array has channels 0
and 2 assigned as drive channels, and channels 1 and 3 assigned as host channels.
You can attach up to two expansion units to a RAID array if channel 1 or channel 3 is
configured as a drive channel. When you configure a host channel as a drive channel,
the primary ID (PID) is set to 8 and the secondary ID (SID) is set to 9. To avoid SCSI
ID conflicts, change the newly assigned drive channel PID to 6 and the SID to 7 using
the firmware application. For details, refer to the
SANnet II Family RAID Firmware
User’s Guide .
This section describes:
■
“Cabling to One Expansion Unit” on page 4-20
■
“Cabling to Two Expansion Units” on page 4-22
■
“Adding an Expansion Unit to an Existing RAID Array” on page 4-24
4.10.1 Cabling to One Expansion Unit
The following figures are examples of configurations that have a RAID array
connected to one expansion unit.
Caution –
A maximum of 16 drive IDs is allowed per channel. Therefore, in a 12-
drive array, do not connect a split-bus channel 0 or channel 2 (6 IDs) to a single-bus
expansion unit (12 IDs).
In Figure 4-27, the RAID array and one expansion unit have been set up for single-bus
configuration; Channel 2, a drive channel, is connected to the expansion unit.