Specifications

ES/OL
Evaluator Series On-Line™
Storage Systems
Product Analysis
May, 2011
Page 18 of 30
Analysis of Fujitsu ETERNUS DX400 S2
Models DX410 and DX440
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The ETERNUS DX400 S2 supports either a fixed path access on a per LUN basis, or dynamic multi-path
access on a per LUN basis. This feature is different than active/active controllers, and different still from multi-
path I/O. The ETERNUS DX400 S2 series permits asymmetric LUN access. This is a mode which Fujitsu
refers to as “Assigned CM.”
The ETERNUS DX400 S2 systems assign a controller module (CM) to a specific RA
ID Group. The path(s) connecting to the controller normally used will have an active status, while the path(s)
connecting to other controllers will have standby status.
Paths connected to the assigned CM are in active status, while paths connected to the non-assigned CM are in
standby status. Load-balancing is performed on the paths in active status (called active paths). Paths in
standby status (called standby paths) are normally not used for access.
Thus, the ETERNUS DX400 S2 provides active/active controller use with multi-pathing, and asymmetric
access to a LUN through a specific array controller (or control module - CM). The diagram below illustrates the
configuration for AIX, although this is also the case for other OS environments. Figure 3 below illustrates
asymmetric access.
Figure 5: Asymmetric MPIO Access for ETERNUS DX400 S2 (Source: Fujitsu)
Solaris
Fujitsu provides a device driver for Solaris platforms supporting MPIO, utilizing Fujitsu’s multi-path driver, or
MPD.
Windows
Fujitsu provides a device driver for Windows platforms supporting MPIO, utilizing Fujitsu’s multi-path driver, or
MPD.