AC&NC | RAID.edu - RAID Levels - RAID Level 1


	Click on the diagram to see RAID 1 in action

For Highest performance, the controller must be able to perform two concurrent separate Reads per mirrored pair or two duplicate Writes per mirrored pair.

RAID Level 1 requires a minimum of 2 drives to implement

One Write or two Reads possible per mirrored pair

Twice the Read transaction rate of single disks, same Write transaction rate as single disks

100% redundancy of data means no rebuild is necessary in case of a disk failure, just a copy to the replacement disk

Transfer rate per block is equal to that of a single disk

Under certain circumstances, RAID 1 can sustain multiple simultaneous drive failures

Simplest RAID storage subsystem design

		Highest disk overhead of all RAID types (100%) - inefficient Typically the RAID function is done by system software, loading the CPU/Server and possibly degrading throughput at high activity levels. Hardware implementation is strongly recommended May not support hot swap of failed disk when implemented in "software"

		Accounting Payroll Financial Any application requiring very high availability