Data distribution in various levels of RAID?

How is the data distributed in various levels of RAID? Explain with the help of some example data. What should be the RAID level for the disk of database server that is used as a backend to store the critical financial information of a company? Give reasons in support of your answer.


The basic idea behind RAID is to combine multiple small, inexpensive disk drives into an array, which yield performances exceeding that of one large and expensive derive. This array of drives will appear to the computer as a single logical storage unit or drive.

RAID is a method in which information is spread across several disks, using techniques such as disk string (RAID Level 0) and disk mirroring (RAID Level 1) to achieve redundancy, lower latency and or higher bandwidth for reading and or/ writing to disks, and minimize recoverability from hard –disk crashes.

Need for RAID: -
RAID provides real-time data recovery when a hard drives fails increasing system uptime and network availability against loss of data. Another advantage of the system is that multiple disks working together increase overall system performance. Any individual or company could benefit from having a RAID recovery system in place.

Level of RAID:-

Level 0:- RAID 0, often called “striping” is a performance –oriented striped data mapping technique. That means the data being written to the array is broken dawn into strips and written across of the member disks of the array.

Level 1:- RAID Level1, or “Mirroring”, has been used longer than any other form of RAID . Level 1 provides redundancy by writing identical data to each member disk of the array leaving a “mirroring” copy on each disk. Mirroring remains popular due to its simplicity and high level of data availability.

Level 4: - Level 4 uses parity (3) concentrated on a single disk drive to protect data. It’s better suited to transaction I/O rather than file transfers. Because the dedicated parity disk represents an inherent an inherent bottleneck, level 4 is seldom used without accompanying technologies such as write-back caching.

Level 5:- The most common type of RAID. By distributing parity across some or all of an arrays member disk drives, RAID level 5 eliminates the write bottleneck inherent in level 4. The only bottleneck is the parity calculation process. With modern CPUs and software RAID, that is not a very big bottleneck.