DriveSpan

I have long wondered why no one has yet brought a utility to market that allows users to simply and safely add a new larger hard drive without the hassle of copying the exiting files to the larger drive so as to take advantage of the extra space. Sure, you can add a new drive but the BIOS will always find it as a separate drive. While the added space is nice, it doesn't much help when you need to install software that adds new libraries to windows and needs to use space that you just don't seem to have.

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Hold on now. Future Systems Solutions Inc. has released one of the most amazing utilities that I have come across. They call it DriveSpan. DriveSpan is a unique PC based utility that allows a user to expand their current drive space by simply installing an additional drive (or drives).

After installing DriveSpan, Windows automatically detects the installation of a new drive, just as Windows does for other hardware devices, and sets up the drive for the user. No partitioning, formatting, or running fdisk . It is all done for you by DriveSpan.

What is unique about DriveSpan is it's patent pending media expansion partition (MEP). This feature allows all, or any portion, of a newly installed drive to be added to the space of the existing drive. This makes increasing drive space quick and easy for almost any user. No cloning, program reinstallation, file moving, etc. just to have more disk space for your programs and files.

For instance.when installing Windows 98, if a user does not have enough disk space and decides to add a larger drive the hassles can be very time consuming. Swapping drives around, moving and reinstalling programs, copying and deleting files - it shouldn't be this hard. With DriveSpan it's not. With DriveSpan the user simply plugs in their new drive, the new drive is detected and setup and a single large drive is immediately available to the user. No second drive letter to deal with, no shifting around of programs and data to make room for large files. Simply install the drive, run the DriveSpan Wizard and start using the new space. It has to be the easiest way to add disk space to an existing PC that there is.

Partitions and the File Allocation Table
Partitions, segments or sections of a disk, which are used to divide and identify the format of the disk. OS's, including Windows, use partitions to indicate which file system must be used to access the disk. DOS and Windows have always used the file allocation table or FAT to properly identify the hard disk's file system for the system to access. Windows 95/98 users are most likely familiar with FAT16 and FAT32. The FAT16 file system uses 16-bit numbers to identify data. A 16-bit number allows a FAT file system to accommodate up to 2G of data. While this capacity is quickly becoming a limitation for today's computers, the FAT16 format still represents the most commonly used file system format in use today. This is the reason that disks that are physically larger than 2GB are divided into two or more smaller logical disks - and why users will often end up with C:>; D:>; etc. drive letters. The most recent version of the FAT file system is FAT32. The FAT32 file system currently uses 28-bit numbers to represent data addresses, which allows for up to 2 terabytes (TB) of data. There are other file systems in use on computers, including NTFS, HPFS, and UNIX, but for now the most commonly used file system for the PC is still the FAT file system.

Features


How DriveSpan Works
DriveSpan works under the file system to combine all of the sectors from two or more disks so that the file system itself can perceive all of the sectors as belonging to a single disk. This technique is not new. It has been used for years on network servers and is most commonly referred to as disk spanning.
DriveSpan brings disk spanning to the desktop PC by creating special partitions to identify disks or regions of disks that have been spanned. DriveSpan refers to these partitions as Media Expansion Partitions (MEP).

Since DOS and Windows cannot recognize MEP partitions, DriveSpan's drivers install before the operating system has completed initialization to provide the necessary support. MEP partitions are serialized in a manner that allows the DriveSpan drivers to present the spanned disks to the operating system as a single disk image. If the boot drive has been spanned, DriveSpan also creates a special "boot" partition on the boot disk to assist in this process.

The small "boot" partition created by DriveSpan contains only the critical system files required to start the operating system. Once the operating system has been booted and the DriveSpan drivers are up and running, this partition is hidden from the operating system. You can now add a new disk to your existing system.

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This design permits DriveSpan to reliably span virtually an unlimited number of disks. Under DOS and Windows, DriveSpan can span up to 2 TB of physical disk space, the maximum currently supported by the FAT32 file system.

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For the user this means that it is possible to add an additional hard disk to a system and have the existing drive, C: for example, expand to a total size of the original and new drive. If a 4GB drive were in the system, and an 8GB drive added, rather than the user now having a 4GB C: drive and an 8GB D: drive, the user is presented with a single 12GB C: drive. This eliminates the need to swap drives, clone disks, move and/or reinstall programs and files.

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DriveSpan's patent pending Media Expansion Partitions offer a safe way for the operating system to write files or parts of files on separate physical disks without worrying about pointer files. Pointer files are used in some storage spanning products to redirect file system requests from one drive to another so that files can be placed on a drive other than the one expected by the operating system. However, this approach brings the risk of data loss if the pointer file is damaged or accidentally deleted.

Because DriveSpan actually creates a partition that spans across multiple hard disks, the operating system sees the files in their actual partitions and no file redirection or pointer files are used. This also means that there is no degradation in performance related to spanning drives. The operating system sees the spanned disks as a single contiguous disk.

DriveSpan is very intuitive and easy to use.  If you want the simplicity of never having to deal with multiple disks again and want an easy, safe, and economical way to accomplish this try DriveSpan.  Once it is properly set up and configured, you won't even have to think about it again.   Definitely the drive utility of the year! approved.gif (5878 bytes)
To find out more about DriveSpan and Future Systems Solutions, check out their web site at http://www.fssdev.com/

June 20, 1999

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