Promise Technology FAST TRAK100TM user manual Striping/Mirror RAID 0+1, About Dual Data Redundancy

FastTrak100 User Manual

Striping/Mirror (RAID 0+1)

A combination of both above array types. It can increase performance by reading and writing data in parallel while protecting data with duplication. A minimum of four drives needs to be installed. With a four-drive disk array, two pairs of drives are striped. Each pair mirrors the data on the other pair of striped drives. The data capacity is similar to a standard Mirroring array with half of total capacity dedicated for redundancy.

About Dual Data Redundancy

One unique (though rarely occurring) feature of RAID 0+1 is dual fault tolerance. In some cases, two drives can fail simultaneously and still maintain the integrity of data. There are six combinations in which two drives can fail. FastTrak100 protects the data array in four of those cases depending on drive type (some drives do not permit the Slave drive to continue to function if the Master drive fails).

Assume the drives are configured as follows (M = Master, A/B indicates which striped pair the drive belongs to, # indicates which part of stripe data):

	IDE 1	IDE2
M	Drive A1	Drive B1
S	Drive B2	Drive A2

69