Wide-Ultra Scsi, Fast-Wide Scsi-2, And Fast-Scsi-2; Array Accelerator - Compaq 219700-001 - ProLiant - 1500 Reference Manual

Wide-Ultra SCSI, Fast-Wide SCSI-2, and Fast-SCSI-2

The SMART-2DH Array Controller complies with ANSI SCSI-2 standards,
supporting 16-bit Wide-Ultra SCSI, 16-bit Fast-Wide SCSI-2, and 8-bit Fast-
SCSI-2 (standard SCSI) devices.
Wide-Ultra SCSI
Wide-Ultra SCSI technology provides SCSI data transfer rates of up to
40-Mbytes/sec at a 20-MHz bus rate. This combination allows high
throughput in many network application environments, including resource
sharing and database servicing.
Fast-Wide SCSI-2 and Fast-SCSI-2
Fast-Wide SCSI-2 provides two bytes of data at each bus transfer, providing a
maximum of 20-Mbytes/sec data rate between SCSI devices while still
maintaining a 10-MHz bus rate.
Compaq Fast-Wide SCSI-2 controllers and devices are able to communicate
using Fast-SCSI-2 protocol when required. Therefore, Fast-SCSI-2 drives may
also be used with SMART-2DH Array Controller using the appropriate cable
adapter.

Array Accelerator

The SMART-2DH Controller Array Accelerator provides a 16-MB onboard
write cache. The result is improved performance on data access to the drive
array by serving as a posted-write cache and read-ahead cache. The write
cache can accept data from the server at 60 megabytes per second. At the
same time, read and writes caches can be accommodated by the drivers. The
read-ahead cache uses a multi-threaded algorithm to predict the next likely
read operation for the array. That data is then read into the Array Accelerator
from the drives. When the SMART-2DH Array Controller receives a read
request for the cached data, it can be brought immediately into system
memory bus speeds. The Array Accelerator feature may be disabled by
software if desired.
Writer: Pamela King Project: SMART-2DH Array Controller Reference Guide Comments: 295469-002
File Name: B-CH01.DOC Last Saved On: 2/27/98 11:23 AM
COMPAQ CONFIDENTIAL - NEED TO KNOW REQUIRED
SMART-2DH Array Controller Reference Guide
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