Before building an array

When building some really big data storage, you should keep in mind the following concerns:

• array size
• fault-tolerance
• speed
• amount of money you are going to spend

Taking into account the above then it is needed to decide if you try to build your own storage unit or just order off-the-shelf data storage. If you choose the latter option then consider at least this one of RAID tips.
If you decide to build your own RAID then check all of the www.raidtips.com.

Does a RAID decrease access time?

Storage device performance is described by:

• access time
• throughput is sustained average speed of data transfer.

We know that RAID0 can increase throughput, as stated e.g. here.

Access time is more tricky. Access time in a regular hard disk includes the time needed to move a read head above the target track (seek time) and the time which is needed a hard disk to bring a sector under a read head (rotational latency).

Regardless of the number of member disks in RAID 0 it may occur that the cache doesn't have a requested sector which in turn is the furthest from the read head. If this sector is needed the access time is the same (not better) as in case of a single drive. If you are willing to improve random access time you should get rid of rotational hard drives and get an Solid State Drive instead.