RAID-1
RAID-1 is shorthand for RAID Level 1: Mirroring and Duplexing.
RAID Level 1 is a type of RAID configuration which uses 2 disks to provide 100% redundancy in case of a single drive failure.
Features:
- Availability: Can tolerate the loss of 1 drive
- Capacity: 50% (2 drives = 1 drive available space)
- Degradation: Slight degradation of read performance during rebuild, write speed actually increases. Rebuilding is fast.
- Performance: Reads are up to twice as fast as a single disk, writes are the same as the speed of a write to the slowest of the 2 disks.
- Summary: Highest fault tolerance / availability, lowest storage capacity
- Typical Uses: Accounting, payroll, financial services, databases servers, highly available services
How it works
- READ: read data from both disks at the same time
- WRITE: write data to both disks, write is complete when both disk writes complete (when writing in synchronous mode)
Comparison with other RAID types:
- RAID-0 has faster writes and equal reads (for a 2-drive RAID-0 set)
- RAID-5 has slower writes and faster reads (as it requires minimum 3 disks, but can read from all 3)
