The #5703 is a SCSI RAID controller that has a 40MB cache and provides RAID-5 protection of internal disks. It also supports internal tape units, CD-ROM, DVD-RAM, and DVD-ROM units.
The #5703 has two SCSI (VHDCI) buses.
In addition to providing RAID-5 protection for disks, #5703 also works as a high-performance controller for disks protected by system mirroring or disks with no protection.
The #5703 supports a maximum of 12 disk units (this total may be limited due to other expansion tower constraints).
A minimum of three disk units of the same capacity are needed for a valid RAID-5 set. A maximum of four arrays are allowed per controller. All disk units in an array must be of the same capacity.
Parity is spread across either two, four, or eight 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 8-12 disk units is started, parity is spread across eight disk units.
The number of arrays and size of each array can be influenced by specifying an optimization of either balance, performance, or capacity in Operations Navigator when starting arrays. An optimization of balance is the default when starting arrays from green screens. If disk units are in cluded into an existing array, parity may be spread across less than the preferred number of disk units. In this case the RAID function must be stopped and then started to redistribute the parity.
The #5703 can control up to two removable media devices (internal tape, CD-ROM, DVD-RAM, and DVD-ROM).