288 iSeries and AS/400e System Builder
#4748
#9748
#4748 PCI RAID Disk Unit Controller
The #4748/#9748 is an Ultra2 SCSI controller with a 26 MB write-cache that provides RAID-5 protection and compression
for internal disk units and supports internal tape units and CD-ROM units. The #4748/#9748 supports both compression
and non-compression modes. The mode of operation is determined by a hardware jumper. The #4748/#9748 is shipped in
non-compression mode. By moving the hardware jumper, the controller functions in compression mode. In addition to
providing RAID-5 protection for disks, the #4748/#9748 is also designed to work as a high performance controller for disks
protected by system mirroring or disks with no protection. The #4748 also supports #4331 1.6 GB Read Cache Device,
which provides increased performance. The #4331 1.6 GB Read Cache Device is supported only when #4748/#9748 is
not in compression mode.
The #4748 does not support data compression on 35 GB disk units.
The #4748 controller supports a maximum of 15 disk units.
The #9748 is the base disk controller for Models 830 and 840.
A minimum of four 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 10 disk units allowed per array. All disk units in an array must be of the same
capacity. Parity is spread across four disk units for arrays of four to seven disk units. Parity can be spread across either four
or eight disk units for arrays of 8 to 10 disk units. For systems started with 8 to 10 disk units in an array, the parity for that
array is spread across eight disk units. For systems that are started with less than eight disk units in an array and later MES
upgraded to 8, 9, or 10 disk units, the RAID function must be stopped and then started before the parity is spread across
eight disk units.
The #4748/#9748 controls up to two removable media devices (internal tape or CD-ROM).
The #4748 can be attached directly to a Linux partition. When installed as #0605 - Direct Attach - #4748 PCI RAID Disk
Unit Controller, an IOP is not required. When attached directly to a Linux partition, the #4748 cannot be accessed by
OS/400 partitions. When attached directly to a Linux partition, the #4748 does not support RAID or hardware disk
compression.
Requires long PCI card slot.
Minimum operating system level: OS/400 V4R5
The #4748 and #9748 are Customer Install Features.
The #4748 and #9748 are withdrawn from marketing on 02 July 2002.The recommended replacement is #2757 PCI-X Ultra
RAID Disk Controller
#4778
#9778
#4778 PCI RAID Disk Unit Controller
The #4778/#9778 is an Ultra2 SCSI controller with a maximum compressed write cache size of 104 MB that provides
RAID-5 protection and compression for internal disk units and supports internal tape units, CD-ROM and DVD-RAM units.
The #4778/#9778 supports both disk compression and enhanced modes. The mode of operation is determined by a
hardware jumper. The #4778/#9778 is shipped in enhanced mode, which enables compression of the write cache and
Extended Adaptive Cache (a Read Cache Device is needed for Extended Adaptive Cache). By moving the hardware
jumper, the controller functions in disk compression mode. Disk compression mode should only be used when disk
compression is desired. In addition to providing RAID-5 protection for disks, #4778/#9778 is also 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 better performance than system checksum.
The #4778/#9778 also supports the #4331 1.6 GB Read Cache Device, which is used by Extended Adaptive Cache to
provide increased performance. The #4331 1.6 GB Read Cache Device is supported only when the #4778/#9778 is in
enhanced mode. The #4778/#9778 controller supports a maximum of 18 disk units.
A minimum of four 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 10 disk units allowed per array. All disk units in an array must be of the same
capacity. Parity is spread across 4 disk units for arrays of 4 to 7 disk units. Parity can be spread across either 4 or 8 disk
units for arrays of 8 to 10 disk units. For systems started with 8 to 10 disk units in an array the parity, for that array, is spread
across eight disk units. For systems that are started with less than eight disk units in an array and later MES upgraded to
8, 9, or 10 disk units, the RAID function must be stopped and then started before the parity is spread across eight disk units.
The #4778/#9778 controls up to two removable media devices (internal tape, CD-ROM or DVD-RAM). The #4778/#9778
is the only disk unit controller that supports compression on 35.16 GB disk units.
System unit and tower disk unit configurations restrict the number of attaching disk units to 15 or less.
The #4778 can be attached directly to a Linux partition. When ordered as #0606 - Direct Attach - #4778 PCI RAID Disk
Unit Controller, an IOP is not required. When attached directly to a Linux partition, the #4778 cannot be accessed by
OS/400 partitions. When attached directly to a Linux partition, the #4778 does not support RAID or hardware disk
compression.
