IBM 6512 Disk Unit Controller for RAID

• SCSI RAID Controller

IBM 6512 is a Fast Wide SCSI controller that provides RAID-5 protection for internal disk units. The #6512 also includes a 4MB write-cache. The #6512 is designed to control Fast Wide and Fast Narrow SCSI disk units that are installed in the: #5051/#5052/#5058/#8052/#9051: Storage Expansion Units, #5080/#5082/#5083: Storage Expansion Tower, #5064/#9364: System Unit Expansion. #6512 offers greater performance than: #6502: Disk Controller for RAID, #6530: Storage Device Controller. #6512 has been replaced by: #6532: RAID Disk Unit Controller, #6533: RAID Disk Unit Controller. In addition to providing RAID-5 protection for disks, #6512 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 #6512 provides a 4MB write-cache, faster microprocessor and memory for increased performance compared with the 2MB write-cache #6502 disk unit controller. The controller supports a maximum of 16 drives. A minimum of four drives of the same capacity are needed for a valid configuration using the RAID 5 disk unit controller. A maximum of two arrays are allowed per controller with a maximum of ten 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 eight 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 following disk units can be placed in a RAID-5 array: #1602: 1.03GB Single Disk Unit Kit, #1603: 1.96GB Single Disk Unit Kit, #4605: 1.03GB Additional Disk Unit, #4606: 1.96GB Additional Disk Unit, #4607: 4.19GB Additional Disk Unit, #4650: 1.96GB Additional 2-Byte Disk Unit, #4652: 1.03GB Additional 2-Byte Disk Unit, #6605: 1.03GB Additional Disk Unit, #6606: 1.96GB Additional Disk Unit, #6607: 4.19GB Additional Disk Unit, #6650: 1.96GB Additional 2-Byte Disk Unit, #6652: 1.03GB Additional 2-Byte Disk Unit, #7607: 4.19GB Optional Base Disk Unit, #9606: 1.96GB Base Disk Unit.