Product Description
IBM 2726 PCI RAID Disk Unit Controller
- SCSI RAID Controller
IBM 2726 is designed to control Ultra, Fast Wide and Fast Narrow SCSI disk and tape units that are installed in the base system unit and the #5064/#9364: System Unit Expansion with #9329: PCI Integrated Expansion Unit. In addition to providing RAID-5 protection for disks, #2726 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 greater performance than system checksums. The #2726 controller supports a maximum of 15 drives. A minimum of four drives of the same capacity are needed for a valid RAID 5 configuration. A maximum of three arrays are allowed per controller, with a maximum of 10 drives allowed per array. All drives in an array must be of the same capacity. Parity is spread across four drives for arrays of four to seven drives. Parity can be spread across either four or eight drives for arrays of eight to ten drives. For systems started with eight to ten drives in an array the parity, for that array, will be spread across 8 drives. For systems that are started with less than eight drives in an array and later upgraded to eight, nine, or ten drives the raid function must be stopped and then started before the parity will be spread across eight drives. The #2726 also supports one CD-ROM and one internal tape unit when placed in the system unit. When placed in the #5064/#9364: System Unit Expansion, the #2726 can support up to three internal tape/CD-ROM units.
