Characteristics & Advantages

• 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

Disadvantages

• 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"

Recommended Applications

• Accounting
• Payroll
• Financial
• Any application requiring very high availability