124 iSeries and AS/400e System Builder
#2780 #2780 PCI-X Ultra4 RAID Disk Controller
The #2780 PCI-X Ultra4 RAID Disk Controller is an Ultra4 (u320) SCSI controller with a maximum compressed write cache
size of 757 MB and maximum compressed read cache of one GB. The #2780 provides RAID-5 protection for internal disks
and also supports internal tape units, CD-ROM, and DVD units. The #2780 has four Ultra4 SCSI buses. In addition to
providing RAID-5 protection for disks, the #2780 PCI-X Ultra4 RAID Disk Controller is designed to work as a high
performance controller for disks protected by system mirroring or disks with no protection.
The #2780 PCI-X Ultra4 RAID Disk Controller supports a maximum of 20 disk units. A minimum of three disk units of the
same capacity are needed for a valid RAID-5 configuration. A maximum of six arrays are allowed per controller, with a
maximum of 18 disk units allowed per array.
All disk units in an array must be of the same capacity. Parity is spread across either two, four, eight, or 16 disk units in an
array. If an array of three disk units is started, parity is spread across two disk units. If an array of four to seven disk units
is started, parity is spread across four disk units. If an array of 8 to 15 disk units is started, parity is spread across eight
disk units. If an array of 16 to 18 disk units is started, parity is spread across 16 disk units.
The number of arrays and size of each array can be influenced by specifying an optimization of either
Balance,
Performance, or Capacity when starting arrays in iSeries Navigator. An optimization of Balance is used by default when
starting arrays from DST or SST options. If disk units are included into an existing array, the number of parity drives does
not increase, so parity can be spread across less than the preferred number of disk units. In this case, the RAID function
must be stopped and then started in order to redistribute the parity.
The #2780 controls up to two removable media devices (internal tape, CD-ROM, and DVD).
The #2780 does not support DASD compression.
The #2780 has a battery that provides concurrent maintenance and improved resiliency.
The #2780 can be attached directly to a Linux or AIX® partition. When ordered as #0627 - Direct Attach - #2780 PCI-X
Ultra4 RAID Disk Controller, an IOP is not required. When attached directly to a Linux or AIX partition, the #2780 cannot
be accessed by OS/400 partitions.
Prerequisite: One 3V long PCI slot is required
Not supported in Slot 1 of #5074, #5079, #5094, and #5294.
Due to system unit and external tower disk unit cage SCSI bus designs, only the Model 270 has a suitable system
configuration to allow 18 disk units to attach to a single #2780. All other system unit or tower disk configurations restrict
the number of attaching disk units to 15 or less.
SCSI port 1 can support LVD or single-ended devices.
SCSI ports 0, 2 and 3 are LVD only.
Minimum operating system level: OS/400 V5R2
The #2780 is a Customer Install Feature
