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IBM System Storage DS3500: Introduction and Implementation Guide
13.1 Planning for iSCSI attachment
In addition to using SAS and Fibre Channel as the interface connection method, iSCSI host
interfaces of DS3500 allow servers with specialized hardware iSCSI cards, or with software
running over regular Ethernet cards, run the iSCSI protocol as the connection method to
attach the DS3500 Storage Subsystems. As with SAS or FC, before beginning an iSCSI
deployment, plan in advance, understand and document the network topology that will be
used.
Hardware initiators
As some iSCSI hardware initiators may be supported for attachment to DS3500 in the future,
check currently supported types and versions at IBM interoperability web site:
http://www.ibm.com/systems/support/storage/config/ssic
Before you install and configure these adapters, make sure that you have installed the latest
management application and the latest firmware code supported by IBM.
Software initiators
Check currently supported iSCSI Software Initiators for various operating systems on IBM
interoperability web site:
http://www.ibm.com/systems/support/storage/config/ssic
Storage Partitioning
Because the SAS/FC and iSCSI protocols provide radically different latency and throughput
capabilities, and this mixture within a server might cause failover driver conflict, performance
degradation, or potential data loss, you have to plan ahead by using the following
recommendations:
Define separated partitions for SAS or FC based hosts from iSCSI based hosts. Avoid
mixing them in same storage partition.
A single host should not be configured for both iSCSI connections and SAS or FC
connections to the storage system.
In order to define hosts and storage partitions in iSCSI, remember that you have to plan for
iSCSI addresses for the host ports, and use the iSCSI Qualified Name (IQN) of the host you
want to map.
Network settings
Unlike traditional Fibre Channel, which requires special cabling and SAN switches, iSCSI can
be run over an existing network infrastructure. However, in complex network environments,
Note: At the time of writing this book there is no iSCSI HW Initiator supported with
DS3500.
Note: The native MPIO that is provided with the Microsoft iSCSI Software Initiator is
supported at the time of writing this book, but we still recommend to use the DSM (MPIO
Device Specific Module) that is provided with the DS Storage Manager software, to make
sure that failover and I/O access are correct. If the native MPIO is used for the Microsoft
iSCSI Software Initiator, it can have unwanted effects in some particular configurations.
Summary of Contents for DS3500
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