1282074762_uchebnik-sdelanyi / ENGLISH / дом чтение / k2

4-9 GB

2-5 GB

9-18 GB

4-10 GB

18-36 GB

10-20 GB

Fibre Channel-Arbitrated Loop UltraSCSI Ultra2SCSI

Fibre Channel-Enhanced Loop Ultra4SCSI

UltraATA

0.06-0.08

Embedded PCI

010-0.14

0.04-0.06

0.08-0.12

0.03-0.05

PC hard disk capacity is expected to climb to 36 GB by the year 2000

markets to develop for Ultra2 SC^I and Fibre Channel. People will use Ultra2 to support their legacy SCSI drives."

A year ago, Seagate and IBM agreed to merge Seagate-backed FC-AL and IBM-backed Serial Storage Architecture (SSA) into one serial storage interface standard dubbed Fibre Channel-Enhanced Loop (FC-EL), combining SSA reliability and FC-AL performance. It could become the dom­inant long-term high-end mass storage interface, with performance moving toward 800 MBps and beyond. Like FC-AL, FC-EL is both a network and a storage inter­face standard, supporting Internet, ATM, and SCSI protocols, among others. The first FC-EL products are expected in 1999.

But don't expect high-end drives that predict and warn you of their failure. Self-Monitoring, Analysis, and Reporting Tech­nology (SMART) is not planned for most workstation and server systems next year. -Nebojsa Novakovic

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PC hard disk capacity is expected to climb to 36 GB by the year 2000.

plans to use the technology in the future. While dual-head parallel operation dou­bles data transfer speed for both reads and writes, similar speedups can be achieved by striping two identical drives on the same or different SCSI connections. Data can be interleaved on a word or sector basis, depending on whether your target appli­cation is graphics- or database-oriented. Windows NT directly supports disk strip­ing, joining the drives into a single volume.

Makers of high-end drives do not need to follow the small incremental steps in capacity seen in IDE drives. Instead of 2.1 GB, 2.5 GB, 3.2 GB, 4.3 GB, etc., the high-end arena has the simple capacity-dou­bling rule: 2.2 GB, 4.5 GB, and 9 GB. The 18-GB Quantum Atlas III is presently the highest-capacity 3.5-inch drive.

UltraSCSI, in its 20-MBps 8-bit and 40-MBps 16-bit versions, is now the dominant high-end mass storage interface. Many high-end drives are available in the most popular versions of this interface, includ­ing combinations of narrow, wide, single connector attachment (SCA), and differ-entiarUltraSCSI. Early next year, volume shipments of the first Ultra2 SCSI drives with new LVD-Link (low voltage differ­ential) transmitter technology will start. The 16-bit version of Ultra2 SCSI not only doubles the transfer rate to 80 MBps, it also increases the maximum cable length from 1.5 to 12 meters. The first PCI controller to provide Ultra2 Wide SCSI with LVD-Link

is Symbios's 53C895 Ultra2 Wide PCI/SCSI I/O processor. The company is expected to offer a dual-channel Ultra2 SCSI processor early next year on a 64-bit PCI bus, the fol­low-on to its 53C876 dual-channel Ultra Wide SCSI PCI processor.

For the next year, there are more design improvements scheduled by the ANSI XT310 committee, including compact packaging, tripled connector density, and "smart silicon." With Ultra4 Wide SCSI, bus bandwidth will increase to 160 MBps.

The Fibre Channel-Arbitrated Loop (FC-AL) provides serial interface perfor­mance of 100 MBps per loop, with up to two loops connected to each storage device. This unprecedented performance rate can be sustained on links up to 10 kilo­meters long, with as many as 126 devices in a single chain. Adaptec and Symbios were among the first to offer FC-AL PCI host adapters earlier this year.

Quantum's Rawcliffe says the 1998 high-end focus will still be on Ultra2 SCSI with LVD, as the performance difference be­tween it and FC-AL is not so drastic, and there will still be around a 20 percent price differential between otherwise identical drives in Ultra2 SCSI and FC-AL versions. Also, FC-AL controllers will still be sub­stantially more expensive, even with sin­gle-chip implementations like the Adaptec AIC 1160 and the Symbios FC920. Adaptec product manager Adam Zagorski states that the company expects "two distinct

Web and Radio Broadcasting

The World Digital Audio Broadcast­ing committee recently established standards for transmitting data over the air. And now, products based on those digital audio broadcasting (DAB) stan­dards are starting to emerge. DAB en­ables the transmission of program-associated data and information

First DAB receiver cards for your PC will be available next year.

services such as traffic and weather up­dates. Its most compelling use, how­ever, could be Web datacasting. Trials of DAB datacasting have been com­pleted in The Netherlands, Finland, and Germany. Commercial services are already running in Sweden and the U.K.

DAB inserts MPEG Layer 2 com­pressed multimedia data into the audio

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