User's Manual

System Storage DS3000 Support CD. Incorrect drive migration might cause loss of
configuration and other storage subsystem problems. Contact your IBM
technical-support representative for additional information.
Redundant drive channel pair
Each RAID controller on the DS3200 has a drive expansion channel that contains
an x4 SAS port. The storage expansion enclosures that are connected to this
connector form a drive channel. The maximum number of hard disk drives that can
be installed in one drive channel is 48. In a dual-controller DS3200, one drive
channel from each controller combines to form a redundant drive-channel pair.
Figure 18 shows an example of a redundant drive-channel pair. If any component of
the drive channel fails, the RAID controllers can still access the storage expansion
enclosures in the redundant drive-channel pair.
Note: In storage expansion enclosures that are connected to a dual-controller
storage subsystem, you must install the optional second ESM to support
dual redundant drive paths.
DS3200
Server
To SAS HBA controller 1 To SAS HBA controller 2
SAS cable
SAS cable
EXP3000
To DS3200 RAID
controller A
To DS3200 RAID controller B
SAS cable
SAS cable
EXP3000
SAS cable
SAS cable
EXP3000
RAID controller B
RAID controller A
Figure 18. Example of a redundant drive path
Chapter 3. Cabling the storage subsystem 27