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Appendix A
BREAKING THE 137 GIGABYTE STORAGE
BARRIER
This appendix provides information about the 137GB storage barrier. It
discusses the history, cause and the solution to overcome this barrier.
A.1
Breaking the 137 Gigabyte Storage Barrier
Capacity barriers have been a fact of the personal computer world since
its beginnings in the early 1980's. At least 10 different capacity barriers
have occurred in the storage industry over the last 15 years. The most
notable barriers seen previously have been at 528 megabytes and then at
8.4 gigabytes.
The most recent barrier which will be surmounted in 2001, is the 137-
gigabyte limit or a single ATA drive. The first ATA devices to exceed 137
gigabytes will be four-platter hard disk drives with 40 gigabytes per
platter, yielding 160 gigabytes per drive. These drives will be available in
the second half of 2001. Later in the same year, capacity will continue to
grow to 60 gigabytes per platter, and a three-disk, 180-gigabyte device
will be available and shipping.
The ANSI NCITS T13 Technical Committee (also known as the ANSI ATA
committee) has broken this barrier by incorporating a proposal from
Maxtor into the ATA/ATAPI-6 draft standard that defines a method for
48-bit addressing on a single drive, giving more than 144 petabytes
(144,000 gigabytes) of storage.
In addition, the proposal from Maxtor that was incorporated into ATA/
ATAPI-6 defines a method for extending the maximum amount of data
that can be transferred per command for ATA devices from 256 sectors
(about 131 kilobytes) to 65,536 sectors (about 33 megabytes). This new
method is particularly useful for applications that use extremely large
files, such as those for A/V or multimedia.
The following sections will describe issues surrounding the 137-gigabyte
barrier and the solution for breaking it.
Maxtor MaXLine II 250/300GB
A-1
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