5486IOA.fm Draft Document for Review October 18, 2004
348 IBM Eserver i5 and iSeries System Handbook
7208-012/222/232/234/342 8mm Cartridge Tape Device
9348-001 ½-inch Reel Tape Device–Rack Mount
9348-002 ½-inch Reel Tape Device–Table Top
9427-21x 8mm Tape Library
#2757 PCI-X Ultra RAID Disk Controller
The #2757 PCI-X Ultra RAID Disk Controller is an Ultra SCSI disk unit controller
with a 757 MB compressed maximum cache that provides RAID-5 protection for
internal disk units. It also supports internal tape devices, CD-ROM, and DVD
units. The #2757 has four Ultra SCSI buses.
The #2757 is designed to work as a high performance controller for disks
protected by system mirroring or disks with no protection. In a RAID-5
configuration, disk unit protection is provided at less cost than mirroring, and with
greater performance than system checksums. DASD compression is not
supported.
The #2757 controls up to two removable media devices (internal tape, CD-ROM,
and DVD).
The #2757 is not supported in the system unit of the Model 520, 550, 570, or
595.
The number of disk units per #2757 varies by configuration:
Up to 20 disk units per #2757 are supported in a #5094 PCI-X Expansion
Tower attached to a Model 520, 550, 570,or 595.
Up to 18 disk units per #2757 are supported in the system unit or external
tower disk cage of the Model 270, 800, and 810.
Up to 15 disk units per #2757 are supported in a #9094 Base PCI I/O
Enclosure attached to a Model 870 or 890.
For all other configurations, contact your IBM marketing representative.
A minimum of three disk units of the same capacity is needed for a valid RAID-5
configuration. A maximum of six arrays is allowed per controller, with a maximum
of 18 disk units allowed per array.
Parity is spread across either two, four, eight, or 16 disk units in an array,
dependent upon the number of disk units started in the array, as represented in
the following table.
Tip: Use the #5702 PCI-X Ultra Tape Controller to attach tape devices with
low voltage differential (LVD) connections.
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