Chapter 2. Architecture and technical overview 73For more information, see “Using the Disk Array Manager” in the Systems HardwareInformation Center at:http://publib.boulder.ibm.com/infocenter/systems/scope/hw/index.jsp?topic=/arebj/sasusingthesasdiskarraymanager.htm2.9.2 External SAS connectionsThe onboard SAS controller in the PS703 and PS704 does not provide a direct accessexternal SAS port. However, by using a 3 Gb SAS Passthrough Expansion Card andBladeCenter SAS Connectivity Modules, two ports on the SAS controller (four in the PS704with a second SAS card on the expansion unit) are expanded, providing access toBladeCenter S Disk Storage Modules (DSM) or an external SAS disk sub-system.The Disk Storage Module, part number 43W3581 feature 4545 must be installed in theBladeCenter S chassis to support external SAS storage devices outside the chassis using theSAS Connectivity Card. No disk drives need to be installed in the DSM to support the externalstorage.2.10 External disk subsystemsThis section describes the external disk subsystems that are supported IBM System Storagefamily of products.For up-to-date compatibility information for Power blades and IBM Storage, go to the StorageSystem Interoperability Center at the following link:http://ibm.com/systems/support/storage/config/ssicFor N Series Storage compatibility with Power blades, go to:http://ibm.com/systems/storage/network/interophome.html2.10.1 IBM BladeCenter S integrated storageA key feature of the IBM BladeCenter S chassis is support for integrated storage. TheBladeCenter S supports up to two storage modules. These modules provide integrated SASstorage functionality to the BladeCenter S chassis.There are two ways to implement the integrated storage solution for BladeCenter S with thePS703 and PS704: Using the SAS Connectivity Module Using the SAS RAID Controller ModuleThese methods are detailed in the following sections.Basic local storage using SAS Connectivity ModuleThe main feature of basic local storage is the ability to assign physical disks in disk storagemodules (DSMs) to the blade server, and create volumes by using the RAID function of theNote: To also use external drives in a RAID array using the embedded SAS controller, thedrives must be formatted to 528 sectors.
