Raid 5 Capacity

RAID 5 is used for database applications that call for a high data storage capacity. Though in raid the array capacity is given by:

(size of the drive) * (No. of disks-1).

It generally, has lots of disk space as all the information i.e. data and parity are stored in all the disks and there is no separate disk reserved for parity information. But when the database requires more capacity, there is no way it can get it. It is feasible to replace a faulty disk but there is no way one could add a disk when there is a space issue.

The only way to fight this raid 5 capacity issue is by adding a few hard disks to your already existing array. It is a very new concept and many researchers have shown deep interest in this field. Adding disks to the array would definitely increase the raid capacity. But the question is how can these disks be added? For 24/7 systems like say “online registration” or e-commerce the database should be working always. So, it is definitely not possible to go offline and then add a hard disk to the array; the process must be online for it to be beneficial.

An addition of a disk in the existing array can be done in such a way that it is invisible to the user. Software, which when installed in the computer provides such a quick and clean transaction environment should be used. Each disk that is being assimilated should be striped with the data of the raid array in such a manner that the overhead is the least. Depending on the amount of data in the array, the striping time may vary.

While adding new disks to the array in order to increase raid 5 capacity, one should first access, how much disks the array can take? Obviously if too many disks are added simultaneously, a large overhead will be created. Always try to add disks of similar size. This is important, as the capacity will get truncated to the size of the disk with the least capacity.

By increasing the Raid 5 capacity, the overall efficiency of the system is increased. It has increased Raid 5 capacity with minimum overhead. As the process is totally online, there is no loss of any serious business transactions. Moreover, the capacity-boosting process is very smooth with no disruption at all.