Dot Hill Systems 200 manual Architecture, Enclosure Modules, Controller Modules

Architecture

SANnet II 200 SCSI arrays use modular design principles. Essentially, each array is a collection of independent modules that operate cooperatively, providing all the necessary array functions. The foundation of every array is the enclosure module.

Enclosure Modules

The primary building block of any SANnet II 200 SCSI array is its enclosure. It consists of a compact metal chassis with internal controller mid-plane and disk mid-plane. The controller mid- plane interconnects the rear-facing FRUs and connects to the SCSI buses of the disk mid-plane. The disk mid-plane provides the internal enclosure connections for the disks. The enclosure securely holds and interconnects other FRUs to create a functional storage system.

The SCSI bus configuration for disks can be set to split-bus or single-bus using an external SCSI cable connection. The default mode is for a split-bus disk configuration. Connecting the included SCSI bus configuration cable joins the split-buses into a single-bus configuration and changes the SCSI ID settings of the disks shown on the label on the front of the enclosure. Use of the split-bus option requires that two separate controller SCSI buses are available for disk use.

The enclosure itself is a FRU with no serviceable components. If the chassis or an internal mid- plane were damaged, all of the other FRUs could be removed and inserted into a replacement enclosure in minutes. There are no critical active components within the chassis or on the internal mid-planes, so the chance of a component failure within an enclosure is very low.

The base and expansion enclosures of SANnet II 200 SCSI arrays appear similar, but they are not interchangeable. It is not possible to convert an expansion enclosure to a base enclosure, or vice versa. The base enclosure and expansion enclosure FRUs are different and unique.

Controller Modules

The SANnet II 200 SCSI array is available with either single or redundant controllers. Each controller has four Ultra160 SCSI channels and 512MB of cache that is battery protected for 72 hours during a power failure. Intelligent caching algorithms and support for RAID levels 0, 1, 0+1, 3, 5, 3+0 and 5+0 provide extensive performance and protection. Support for up to 128 LUNs per array ensures flexibility and simplified configuration.

FIGURE 4: Module Locations (rear panel)

The SCSI channels of SANnet II 200 SCSI array controllers can be configured for use with disks or hosts. At least one SCSI channel must be configured for disks and another SCSI channel for hosts. The remaining two SCSI channels can be configured for use with disks or hosts as required.

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