Why RAID 1?

[scott_417]

As it is well known that the RAID 1 is for the Fault Tolerance. It uses disk mirroring, which provides 100% duplication of data. Offers highest reliability, but doubles storage cost. My questions are,

1)How important/necessary is this 100% duplication of data? Wouldn't it be a over-kill?

2) What is the difference beween the external tape backup of the data and this 100% duplication of data on the disk?

3) Is the RAID 1 automatically implemented by the disk controller only?


Thanks to help.

[Steven Clementi · Accepted solution]

Scott:


1. If you lost your main OS disk on a server that was hosting a money transfer application that passed millions of dollars between international banks and markets on a daily basis, would you want to have a 100% duplicated disk waiting in the wings?

The importance/necessity is varied from company to company. If my company lost a production server, it could mean the loss of hundreds of thousands of dollars per minute. Not all companies need immediate or near immediate recovery/redundancy.

2. Faster Recovery if your disk is 100% duplicated. Even more important, potentially no downtime and/or loss of data in the interim.

3. RAID 1 can be implemented via Hardware or Software. Software RAID is generally more expensive in the sense that it uses more system resourses work. Hardware RAID is limited to the resourses of the RAID controller, not effecting the OS.


Steven

[e4services]

You are looking at the thing from the wrong perspective. The RAID 1 is not for backup of data, it is to protected againt a single drive failure. One drive fails, the system continues on the remaining drive.
Your backup protects you from TOTAL data lost, in our example, the failure of both drives.