Server Controllers and Mass Storage Devices

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Controllers

Controllers (or adapters) are devices that manage the communication interface by adapting

or bridging the data from one I/O bus to another. As an added benefit, controllers can also

organize and protect the data stored on the disks through mirroring, duplexing and/or RAID

techniques. The implementation of these data protection techniques is discussed in the

next section of this paper and on page 8.

Controllers are available in three different form factors:

• Embedded on a motherboard

• As a card in a standard bus slot

• Incorporated into an external storage unit

Examples of each of these forms include:

• Embedded

−

SCSI I/O chips

−

Embedded RAID in the HP NetServer LH 3 and LH 4 using SCSI I/O chips and a

microprocessor

• Adapter Cards

−

HP NetRAID which adapts (or bridges) between PCI and SCSI and also provides

RAID

−

HP FC HBA (Fibre Channel Host Bus Adapter) which adapts between PCI and FC

−

HP SCSI HBA which adapts between PCI and SCSI

• Incorporated in an external storage unit

−

HP FC Array which adapts between FC and SCSI and also provides RAID