Western Digital WDE2170 - Manual (Page 29)

WD Enterprise WDE2170/WDE4360 Advanced Product Features
4079-001045 Rev. B RELEASED 04-08-97 21
3. A DVANCED P RODUCT F EATURES
3.1. Compatibility Testing
Western Digital performs extensive testing in its Functional Integrity Test Lab (FIT
Lab™). By equipping the FIT Lab with multiple host systems, adapters, operating
systems, and application programs, compatibility is achieved with a broad range of
applications implemented on workstations, servers, multi-user, and array systems.
3.2. SCSI-3 SPI Compliant
Drive models WDE2170 and WDE4360 conform to the SCSI-3 SPI (SCSI Parallel
Interface) standard. The drives also support the Ultra SCSI performance specification
and are offered in several configurations, such as Ultra Fast (8-bit, 50-pin; up to
20MB/s) and Ultra Fast Wide (16-bit, 68-pin, 80-pin SCA-2; up to 40MB/s) host
transfer rates.
3.3. Embedded Servo Control
The WD Enterprise drives feature embedded servo technology to generate accurate
position information on every track. An embedded servo system has servo bursts
interspersed with customer data on every track. This provides a tight coupling between
head positioning and customer data – a necessity for good soft error rates. In addition,
embedded servo technology is less susceptible to thermal shifts of the system since
customer data and position information are recorded together on the same track.
3.4. Read Caching and Pre-Fetch
Read caching allows the drive to maintain data in the cache for quick transfer to the host
when a media access is not required. Pre-fetching takes place after a media access when
the drive reads data into the cache that the firmware determines as likely to be requested
by the host. Refer to the Western Digital SCSI Implementation Guide (document number
4096-001116) for further details.
3.5. Write Caching
Write caching gives the host the ability to allow the drive to asynchronously write data
to the media while other processes may occur. Refer to the Western Digital SCSI
Implementation Guide (document number 4096-001116) for further details.
3.6. 512 Kilobyte Data Buffer
The entire data buffer is user accessible, enabling powerful data caching capabilities.
3.7. Adaptive Caching
The drives are equipped with an adaptive caching capability which enables them to
improve performance and throughput based on how the drive is being used. Each drive
determines the environment in which it is being used and optimizes the way it handles
commands and data.