My experience with RAID testing

I have been working on the RAID testing for the past couple of months.
I am trying to share the various phases that I had gone through in the past.

The meaning of RAID is Redundant Array of Independent disks. It is basically
meant for providing redundancy when there is a failure of the other drive.

Dell provides various servers with different RAID models. Some examples include
CR100 model. R200 model. Power edge 2950 model etc

If you take the Dell R200 model, it has a RAID type of 2 and it consists of two disks
of same size and capacity.

Whenever a software or data is written in one of these disks the same will be parallely
copied to the other disk. So that providing redundancy at any point in time.

If there is a failure of one disk, the same can be replaced with another new drive.
The data from the master drive will be copied to the new drive and making the
redundancy work.

Dell also provides the power edge models where in the redundancy is spread across more than
two disks, like 4 disks and sometimes 6 disks.

In case of a 4 disk model, assuming each disk is 100GB, the total capacity is 200GB, remaining two drives will be mirrored.

At any point in time the data from the first 100GB harddisk is copied to the other 100GB harddisk. Same way with other two disks also.

In order to identify which disk is mirrored to another disk, you can pull one disk and reinsert the same. The leds in two of the disks will be blinking fast. With this you can identify the rebuild is happening between mirrored drives.