The basic idea of RAID (Redundant Array of Inexpensive Disks) is to combine multiple hard disk drives into an array of drives, which yields performance greater of that of a single drive. Additionally, this array of drives appears to the computer as a single logical storage unit or drive.

The primary benefit of RAID is the increased speed in transferring data.  A secondary benefit depending on the level of RAID implemented is fault tolerance or data mirroring.

What is Striping?                                       

Striping or RAID Level 0 is a method of connecting multiple drives into one logical storage unit.   Striping involves partitioning each drive's storage space into "stripes" or areas on the disk, which may be as small as one sector (512 bytes) or as large as multiple gigabytes. These stripes are then interleaved, so that the combined space is composed alternately of stripes from each drive. In effect, the storage space of the drives is shuffled like a deck of cards.

What is Mirroring?                                       

Mirroring or RAID Level 1 is simply a pair of disk drives that store duplicate data, but appears to the computer as a single drive. Writes must go to both drives in a mirrored pair so that the information on the drives is kept identical. Each individual drive, however, can perform simultaneous read operations. Mirroring thus doubles the read performance of an individual drive and leaves the write performance unchanged.

Should I use Striping or Mirroring?

Striping is the fastest and most efficient array type but offers no fault-tolerance. Striping is commonly used by people seeking top disk drive performance: Digital audio and video, large graphics and pre-press users and users looking to Stripe hardware RAID controllers together for even greater speed gains.

Mirroring is the array of choice for performance-critical, fault-tolerant environments. People who require fault tolerance commonly use mirroring. Banking and financial institutions, enterprise-level applications, medical imaging or basically anyone looking for a real-time backup of their data.

Do I have to Stripe or Mirror the XtraFire Multi-Drive?

No.  You can set up the drives as independent, multiple drives.  The performance will not be as fast as Striping & you will not get the Fault-tolerant benefits of Mirroring, but it does offer the benefit with the removable bays to remove any drive without affecting a RAID array.

What are the hard drive specifications in the XtraFire enclosures?

The 3.5" hard drives used in the XtraDisk firewire drives are typically Maxtor, IBM, Western Digital or Fujitsu hard drives.  They typcially have the following specifications:

• Ultra DMA 100

• Rotational Speed: 5400 or 7200 RPM

• Seek Time (Avg): < 9.0ms

• 2 MB SDRAM Cache Buffer

• MTBF: More than 500,000 power-on hours

• As of October 2002, the new 3.5" hard drives come with a 1 year or 3 year factory-direct warranty.