5486IOA.fm Draft Document for Review October 18, 2004
378 IBM Eserver i5 and iSeries System Handbook
The #2782 is withdrawn from marketing in October 2004. The #2787 PCI-X
Fibre Channel Disk Controller is the recommended replacement.
#2782 PCI-X RAID Disk Unit Controller
The #2782 PCI-X RAID Disk Unit Controller is an Ultra SCSI disk unit controller
with a 40 MB cache that provides RAID-5 protection for internal disk units. It also
supports internal tape devices, CD-ROM, and DVD units. The #2782 has two
Ultra SCSI buses.
The #2782 is designed to work as a high performance controller for disks
protected by system mirroring or disks with no protection. In the RAID-5
configuration, disk unit protection is provided at less cost than mirroring, and with
greater performance than system checksums.
The #2782 controller supports a maximum of 12 disk units. DASD compression
is not supported.
The #2782 controls up to two removable media devices (internal tape, CD-ROM
and DVD).
A minimum of three disk units of the same capacity are needed for a valid
RAID-5 configuration. A maximum of four arrays are allowed per controller, with a
maximum of 12 disk units allowed per array.
Parity is spread across either two, four, eight, or 16 disk units in an array, as
represented in the following table.
Important: A #2766 PCI Fibre Channel Disk Controller, supported on the
iSeries with OS/400 V5R1, can be used to attach the IBM TotalStorage
Enterprise Storage Server (ESS). The #2766 is not supported as a load
source IOP in secondary (system is unable to IPL via a #2766), but remote
load source mirroring is supported through the #2766.
Note: Due to a system unit and external tower disk cage designs, only the
Models 270 and 810, and the #0595/#5095 PCI-X Expansion Tower have a
suitable system configuration to allow 12 disk units to attach to a single #2782.
All other system unit and tower disk configurations restrict the number of
attaching disk units to 10 or less.
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