User guide

4. ARCHITECT AND CONFIGURE YOUR DDN STORAGE ARRAY

Determine the LUN mapping configuration required for each host and architect the storage

layout and mapping required. Storage architecture and host connectivity implementation

details are beyond the scope of this guide. Each application requirements will demand different

implementations. This document focuses on concepts required to achieve the primary goals of

linux multipathing:

Target device path failover redundancy

Storage controller failover redundancy

Preferred target device path optimization

Target device path load balancing across multiple preferred paths

4.1 OVERVIEW OF LUN PRESENTATION PROCESS ON S2A 9900

Refer to the S2A 9900 User Guide for full descriptions of the commands and options available.

A simple example below with four LUNS is provided for illustration purposes. Note that LUN

ownership is optimally balanced across the two controllers. The same principles are identical

for Fibre Channel and Infiniband S2A 99000 models:

Logical Unit Status

Capacity Block

LUN Label Owner Status (Mbytes) Size Tiers Tier list

-----------------------------------------------------------------------------

1 lun_1 1 Ready 3815470 512 1 1

2 lun_2 2 Ready 3815470 512 1 2

3 lun_3 1 Ready 3815470 512 1 3

4 lun_4 2 Ready 3815470 512 1 4

On S2A 9900 Linux multipath configurations, preferred access to LUNs will be automatically be

assigned to host paths serviced by the owning controller.

To implement S2A 9900 controller failover on Linux, it is important to zone S2A 9900 LUNs from

ports both controllers.