by August 11, 2001 0 comments

A hard disk that can store up to 120 billion books, or 144 PB (Petabytes)–read 144,000,000 gigabytes–of data. Jumbo, but not impossible anymore.

Large enterprise storage solutions, like NAS (Network Area Storage) and SAN (Storage Area
Network), let you store enormous amounts of data, by combining many hard disks, and at an equally huge cost. What is path breaking now is that it will be possible to store gargantuan amounts of data on regular PCs that you and I use every day, on the familiar hard disk.

The PC hard disk uses the ATA interface to communicate with the rest of the machine. Currently, we are at ATA 100, with a maximum capacity of 137 GB per disk. The breakthrough that we talk of is being made possible because a new ATA interface standard for locating information on a hard drive is being developed that breaks the present 137 GB barrier. This standard, the ATA/ATAPI-6, allows for up to 48 bits of address space (up from the present 28) on a single drive. Such a device can potentially store up to 144 PB of data. This is 100,000 times more than can be accessed under the present standard. At the same time the new standard remains compatible with current ATA

Big Numbers

131 kilobytes = 131,000 bytes
(a little more than 30 pages of text)
33 megabytes = 33,000,000 bytes
(more than 8,000 pages of text or 25 three hundred-page books) 
137 gigabytes = 137,000,000,000 bytes
(more than 100,000 books, or the contents of a good library) 
2.2 terabytes = 2,200,000,000,000 bytes
(almost 2,000,000 books, or about the content of the Library of Congress, USA) 
144 petabytes = 144,000,000,000,000,000 bytes
(120 billion or 120 x 1,000,000,000, books, more than all that man has written)
Extracted from

These new drives will satisfy the ever-growing demand for space by storage-intensive applications like digital video, MP3, and other multimedia applications, data warehousing, and application servicing. In the case of enterprises, this will help meet storage needs in far less physical space.

You can have a hard disk that can store all the data in the world, but it won’t really matter if your system can’t access it. For instance, 160 GB capacities are already being squeezed onto drives with as many as four platters, but it’s not of much use because a PC can read only the first 137 GB on that drive. This inability to access the entire drive is called a capacity barrier. Capacity barriers have existed since the beginning of the personal computer, with a new barrier being reached, on an average, every six years. Two of the most prominent barriers in the past have been at 528 MB and 8.4 GB. The present one, of course, is at 137 GB.

Barriers result from limitations in OSs or the BIOS (Basic Input/Output System), preventing systems from recognizing drives larger than a certain size. Now that the 137 GB barrier is poised to be overcome, OS developers will need to increase storage device addressing up to 48 bits or more. Most OSs today, like many flavors of Linux, Mac OS 9.x, Windows 95/98/ME/NT 4/2000/XP, are based on 32 bit addressing. The BIOS developers, too, will need to upgrade their products.

This interface initiative by Maxtor, called the Big Drive, has been incorporated by the T13 Technical Committee (responsible for all ATA storage interface standards) into the ATA/ATAPI-6 draft standard that it is developing. Others involved in this initiative are Compaq, Microsoft, and VIA Technologies.

Juhi Bhambal

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