What is RAID 1: Mirroring Hard Drives?

Raid 1, or mirroring, is the strategy of writing the very same information to a lot more than 1 disk drive. Mirrors are usually utilised to guard against information loss due to drive failure. Every drive in a mirror includes an identical copy of the information. When an individual drive fails, the mirror continues to work, providing information from the drives that are still functioning. The laptop keeps operating, and the administrator has time to replace the failed drive without user interruption.

Two widespread scenarios are illustrated in these examples. The 1st creates a mirror out of two new drives and uses it as a replacement for an existing single drive. The second example creates a mirror on a single new drive, copies the old drive’s data to it, then inserts the old drive into the mirror. While this process is slightly far more complicated, it only needs a single new drive.

An exact copy (or mirror) of a set of data on two disks. This is useful when read overall performance or reliability is much more important than information storage capacity. Such an array can only be as large as the smallest member disk. A classic RAID 1 mirrored pair consists of two disks.

An instance of the elevated reliability that a RAID 1 set of mirrored disks can offer can be illustrated with a simple two-disk set of identical drives. Assume the failure rate for any one drive is ten percent more than its expected lifetime. The possibility of each drives in the set failing at the same time would be (ten %) raised to the energy of two (the number of disks in the set). The resulting efficient reliability becomes a one particular % chance of failure over the anticipated lifetime. Add a third disk to the RAID 1 mirrored set and the resulting opportunity of failure drops to .1 percent.

A RAID 1 array ought to not be confused with a backup of your data. RAID 1 especially addresses failures lead to by hardware, and can do absolutely nothing by itself to recover files you may possibly have deleted by error, or that became corrupt due to application crashes or other issues. RAID 1 is an precise copy, so as soon as a file is deleted, it is deleted from all members of the RAID 1 set.