Raid 1 Arrays - Adaptec 4000SAS Installation And User Manual

RAID 1 Arrays

A RAID 1 array is built from two disk drives, where one disk drive is a
mirror of the other (the same data is stored on each disk drive).
Compared to independent disk drives, RAID 1 arrays provide improved
performance, with twice the read rate and an equal write rate of single
disks. However, capacity is only 50 percent of independent disk drives.
If the RAID 1 array is built from different- sized disk drives, the free
space, drive segment size is the size of the smaller disk drive, as shown
below.
Disk Drive 1 250 GB
Disk Drive 2 400 GB
Disk Drives in Logical Drive
Appendix B: Understanding RAID
Drive Segment Size (Smaller Disk Drive)
Disk Drive 1 1 – 250
Disk Drive 2 1 – 250
Not Used
RAID 1 Logical Drive = 250 GB
81
Unused Space: 150 GB