Product manual

CDA 7 5630 Product Manual
2-10 77 A1 69UP Rev00
NOTE:
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2.4.4 Disk Director
The CDA 7 disk director provides an interface between cache and the disk devices.
The CDA 7 contains two disk directors. Each director, with its two advanced
microprocessors, supports up to sixteen 23 or 47 GB 3.5-inch disk devices— one to
four disk devices per SCSI bus (C, D, E, and F).
The CDA 7 supports the following:
CDA 7
Number of Disk Directors 2
Maximum Number of Disk Devices 32
Number of Buses per Disk Director 4
Maximum Number of Drives per Bus 4
Maximum Number of Drives per Director 16
Each disk director provides an alternate path to the disk devices of its disk director
pair. That is, should the primary path through a disk director to a disk device fail,
CDA 7 accesses that device through the other disk director in the pair via its
dual-initiator function. Refer to Dual-Initiator Feature later in this document for
more information on this data availability feature.
2.4.5 Cache
Memory is a crucial component of the CDA 7 system. All read and write
operations transfer data to or from cache. Any transfers between the host processor,
channel directors and cache are achieved at much greater electronic speeds than
transfers involving disks. CDA 7 optimizes data movement between disk and
cache, resulting in the highest performance possible.
Each cache memory card has two cache buses, x and y, with each having a 360 MB
bandwidth for a total processing bandwidth of 720 MB per second. The CDA 7 has
two slots dedicated to cache memory. The subsystem supports a maximum of 8,192
MB of cache. Individual cache memory cards are available in 512 MB, and 1 GB, 2
GB, and 4 GB sizes