Tuesday, January 09, 2001

RAID

RAID, quite simply, is short for Redundant Array of Inexpensive Disks. In less simple terms, it is a system designed for the speedy and secure storage of data, accomplished by spreading that data across multiple, inexpensive drives. RAID 0, also known as stripping mode, doesn't include any data redundancy, but is quite fast. RAID 1, or mirroring mode, offers greatly increased data security by making identical copies of the same data on 2 different drives. As you might expect, RAID 1 is slower at writing data simply because it involves writing every bit of information twice.

Installation of RAID

In order to simplify the task of setting up RAID, you can follow one of two methods:

RAID 0 stripping: In this mode, the total amount of space that will ultimately be available is equal to sum capacity of the two drives involved. Files are written in part on one drive, and in part on the other. The loss of either drive renders the system inoperable.

To setup a RAID system for stripping mode, its necessary to boot from the proper start-up diskette. Once the RAID menu appears, hit Control H and select stripping mode by following the instructions provided with the motherboard. Once that's done, reboot in MSDOS mode, and partion the drive as you see fit (only a single drive will appear to be available, but it will have twice the capacity). Once partitioned, format the first partition using the format c: /s command. Finally, using a CDROM or a backup drive, reinstall the OS.

RAID 1 mirroring: In this mode, the total space available will be equal to that of one of the two drives. Each file is written to each drive. The loss of one results in no data loss, and the system can operate without skipping a beat.

To setup the system for RAID mirroring, start by booting from the proper system disk. Once the RAID menu appears, hit Control H and select mirroring mode by following the instructions provided by the program. Once that's done, reboot in MSDOS mode, and partion the drive as you see fit. Once partitioned, format the first partition using the format c: /s command. Finally, using a CDROM or a backup drive, reinstall the OS.

RAID 0/1 stripping-mirroring: In this mode, 4 drives are put to use, and the total space available is equivalent to half the sum of their total capacity. If 4 20GB drives are used, then 40GB will ultimately be available. Each file is written once to each pair of drives, and then stripped across the two. The loss of a drive causes no data loss, and the system can continue to operate without a hitch.

To setup the system for RAID stripping-mirroring, start by booting from the proper system disk. Once the RAID menu appears, hit Control H and select 0/1 mode by following the instructions provided with the motherboard. Once that's done, reboot in MSDOS mode, and partion the drive as you see fit. Once partitioned, format the first partition using the format c: /s command. Finally, using a CDROM or a backup drive, reinstall the OS.

Next: The tests