Challenge Raid Storage-Control Processor; Figure 1-4 Challenge Raid Server With One Sp - Silicon Graphics CHALLENGE RAID Owner's Manual

Chapter 1: Features of the CHALLENGE RAID Storage System
6

CHALLENGE RAID Storage-Control Processor

The storage-control processor (SP) is a printed circuit board with memory
modules that resides in the storage-system cabinet. It controls the disk
modules in the storage system through a synchronous SCSI-2 bus. An SP has
five internal fast/narrow SCSI buses, each supporting four disk modules, for
a total of 20 disk modules.
Figure 1-4 diagrams a CHALLENGE RAID storage system with one SP.
CHALLENGE server
SCSI-2
interface
Figure 1-4 CHALLENGE RAID Server With One SP
For higher performance, a CHALLENGE RAID storage system can support
an additional SP. The second SP provides a second path to the storage
system, so both SPs can connect to the same host or two different hosts, as
diagrammed in Figure 1-5 and Figure 1-6. With two SPs, the storage system
can support storage system caching, whereby each SP temporarily stores
modified data in its memory and writes the data to disk at the most
expedient time.
Note that the disks are owned by the SP, and not by the host, the SCSI-2 bus,
or the storage system.
SCSI-2 bus
SP A
CHALLENGE RAID