iSeries I/O adapters and controllers 365Draft Document for Review October 18, 2004 5486IOA.fmA minimum of three disk units of the same capacity are needed for a validRAID-5 configuration. A maximum of four arrays are allowed per controller, with amaximum of 12 disk units allowed per array. All disk units in an array must be ofthe same capacity. Parity is spread across either two, four, or eight disk units inan array. If an array of three disk units is started, parity is spread across two diskunits. If an array of four to seven disk units is started, parity is spread across fourdisk units. If an array of 8 to 12 disk units is started, parity is spread across eightdisk units.The number of arrays and size of each array can be influenced by specifying anoptimization of either Balance, Performance, or Capacity in Operations Navigatorwhen starting arrays. An optimization of Balance is used by default when startingarrays from the green screens. If disk units are included into an existing array,parity may be spread across less than the preferred number of disk units. In thiscase, you must stop and then start the RAID function to redistribute the parity.The #5703 can control up to two removable media devices (internal tape,CD-ROM, DVD-RAM, DVD-ROM).The #5703 PCI-X RAID Disk Unit Controller is the recommended replacement forthe #2782 PCI-X RAID Disk Unit Controller.When used as a Direct Attached Adapter, order the #0628 in place of the #5703.The #0143 Disk Controller Placement Exception is a prerequisite for the #5703.#5704 PCI-X Fibre Channel Tape ControllerThe #5704 PCI-X Fibre Channel Tape Controller provides Fibre Channelattachment capability for external tape devices. The #5704 supportspoint-to-point and arbitrated loop topologies and has an LC-type cable connector.Each #5704 is shipped with a wrap connector (part number 05N6767). The#5704 supports 64-bit, 133 MHz PCI-X bus speeds.The following adapter kits are required when connecting SC-type cables to the#5704: #0371 - LC-SC Adapter Kit (50 micron)Restriction: Due to a system CEC and external tower disk unit cage SCSIbus designs, only Models 270, 800, and 810, and the #0595/#5095 PCI-XExpansion Tower have a suitable system configuration to allow 12 disk units toattach to a single #5703. All other CEC and tower disk configurations restrictthe number of attaching disk units to 10 or less.
