108 IBM System Storage DS3500 Introduction and Implementation Guide
Using in-band management through the host-agent has the following advantages:
򐂰 Ethernet cables do not need to be run to the controllers’ management ports.
򐂰 A host name or IP address must only be specified for the host instead of for the individual
controllers in a storage system. Storage systems that are attached to the host can be
automatically discovered.
Using in-band management through the host agent has the following disadvantages:
򐂰 The host agent uses a special logical drive, called the access logical drive, to
communicate with the controllers in the storage system. The access logical drive is
mapped to the host server that you use for in-band management, Therefore, the host
server is limited to one less logical drive than the maximum number that is allowed by the
operating system and the host adapter that is being used.
򐂰 Not all operating systems support the access logical drive. In-band management is not
supported on these systems.
򐂰 You will be unable to manage or monitor the DS3500 storage subsystem if there is a fault
with the host I/O connection between the DS3500 storage subsystem and the host server.
4.8 Host attachment
In this section, we describe the general rules that you should follow when cabling the hosts
and DS3500 storage subsystem. We also describe the general rules for Fibre Channel switch
SAN zoning and iSCSI LAN connections. We provide examples of the various host
attachment implementations with both single and dual controller DS3500 storage subsystems
using SAS, Fibre Channel, and iSCSI.
The specific implementation details for the various host connections, including SAN zoning
requirements and associated prerequisites, are described as required in the specific host
configuration chapters later in this book.
The DS3500 supports multiple-host, multiple-port, and multiple-fabric (Fibre Channel or
iSCSI, and SAS) configurations. In other words, the DS3500 storage subsystem supports
simultaneous SAS and either iSCSI or Fibre Channel host connections with the optional
iSCSI or Fibre Channel host adapter installed, up to a maximum of 64 hosts. Figure 4-21 on
page 109 shows an example of this type of configuration with one direct-attached SAS host,
and one fabric-attached iSCSI or FC host.
Note: If you have a dual controller DS3500 storage subsystem, you must ensure that each
host server has a path to both controllers. A configuration where a host server is only
connected to one controller of a dual controller DS3500 storage subsystem is not a
supported configuration. This requirement applies to SAS, FC, and iSCSI attachment.

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