Quantum, Intel develop protocol to double data transfer rates
By Tom Quinlan
Publication Date: July 8, 1996 (Vol. 18, Issue 28)
A new drive protocol designed to double the data transfer rate of PC-based hard drives is being put forward by Quantum Corp. with
considerable support from Intel Corp. (See "Intel, Quantum double data transfer rate," July 1, page 3.)
The protocol, known as Ultra DMA/33, will double the burst data transfer rate of ATA/IDE hard drives to 33MBps, according to the
two companies.
Although sustained data transfer rates under the new protocol have not yet been specified by Quantum, a representative said they were expected to double as well.
Currently, both the DMA 2 and the PIO Mode 4 support burst-data transfer rates of 16.6MBps. Top-of-the-line disk drives with low
latencies, fast seek times, and rotational speeds of 7,400 rpm offer sustained data transfer rates between 7.5MBps and 8.9MBps.
The new protocol will be backward compatible with the existing Fast ATA/Enhanced IDE specification and will work with existing devices, Quantum officials said. Those devices will include IDE-based peripherals, such as CD-ROM drives, although they won't take advantage of the increased capability of the specification.
Quantum predicted that the cost of DMA/33 drives would be similar to -- or only slightly higher than -- that of existing drives, but the
company declined to outline specifically how drive manufacturers could take advantage of the faster protocol. Because of the faster
throughput rates, Quantum officials said the size of the memory buffers supporting the drives could become smaller.
Burst-mode transfer rates are more useful in speeding up short transactions using the drive, said Jim Porter, senior industry analyst
at DiskTrends Inc., a research company based in Mountain View, Calif.
Users will also benefit from improved sustained data transfer rates when accessing large or sequential files, such as multimedia files.
Server-based storage will get less benefit from the drive specification, Porter said, because in dealing with multiple simultaneous hits over a network, seek times and latency are more important than higher throughput to performance.
"But if you have someone trying to access a large amount of graphics data across the server, which happens frequently these days, then it does become an issue," Porter said.
Quantum is currently applying for a patent on the protocol and will make the specification available in October for free. The first
products are expected to arrive in 1997.
Intel and Via Technologies Inc. have already committed to incorporating support for the new drive protocol in their chip-set lines.
Quantum, in Milpitas, Calif., can be reached at (408) 894-4000.
* Companies supporting DMA/33 include IBM, Seagate, and Western Digital.
infoworld.com
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