Specifications

For detailed information about the ESS, see the IBM TotalStorage ESS Introduction
and Planning Guide.
You get redundancy with the IBM Subsystem Device Driver (SDD). The SDD
resides in the host server with the native disk-device driver for the IBM ESS. It uses
redundant connections between disk storage server and host server in an ESS to
provide data availability and performance.
The Subsystem Device Driver provides the following functions:
v Enhanced data availability
v Automatic path failover and recovery to an alternate path
v Dynamic load balancing of multiple paths
v Path selection policies for the AIX operating system
v Concurrent download of licensed internal code
For more information about the IBM Subsystem Device Driver, see the following
Web site:
ssddom01.storage.ibm.com/techsup/swtechsup.nsf/support/sddupdates/
Host systems that the ESS supports
The ESS provides heterogeneous host attachments so that you can consolidate
storage capacity and workloads for open-systems hosts, S/390 hosts, and zSeries
ERserver hosts. The ESS supports a maximum of 16 host adapters. You can
configure the for any intermix of supported host adapter types.
The following sections contain more information about the following types of host
attachments:
v SCSI-attached open-systems hosts
v Fibre-channel (SCSI-FCP) attached hosts
v ESCON-attached IBM S/390 and zSeries hosts
v FICON-attached IBM S/390 and zSeries hosts
Front view
Rear view
Figure 2. ESS Expansion enclosure, front and rear views
Chapter 1. Introduction 3
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