Piriharan Karthigesan

Question

Describe the various versions of RAID, and which type you would use to obtain the maximum redundancy and security, without sacrificing speed of access to data.

What is a RAID?

• Redundant Arrays of Inexpensive Disks.

In single word “RAIDS” can be known as a disk which provides data’s storage in many different disks.

RAID 0

In RAID 0 the data is divided into blocks that are written to all disks in the array. Using multiple disks at the same time the RAID 0 offers superior I/O performance and this kind of performance can be improved by using multiple controllers most probably a disk controller.

Advantages of RAID 0

• RAID 0 has a very great performance in both writing and reading data.
• Easy implementation of the technology
• No disk overhead and most importantly all the storage space will be used
• Cost wise it is very effective

Disadvantage of RAID 0

• If a drive fails, the chance of losing the data is high
• Fault tolerance

RAID level 1

In RAID 1 the data is always stored twice to write in the data drive and a mirror drive. And in case if a drive or disk fails the controller uses the data drive or the mirror drive for data recovery and continues the operation.

For RAID 1, we at least need two drives.

Advantages of RAID 1

• Data are being stored in both drive where the loss of data is very low
• Good transfer rate
• If a drive fails, there a lot of chance to get the data back to a replacement drive and it is a simple technology

Disadvantages of RAID 1

• Inefficient or unproductive
• Expensive
• Hardware implementation is highly needed for RAID 1
• Data gets written twice in this RAID

RAID level 2

Raid level 2 is used as bit level striping and this RAID is similar to RAID 5. This raids performance is poor and this raid needs at least 10 drives to setup.

Advantages

• Data error correction
• The design of this RAID is simple and easy
• Data transfer is good

Disadvantages

• Expensive

RAID level 3

This is also like RAID 5 but this drive requires a reader dedicated to parity and RAID 3 is very rarely used except based on more specialized or processing environments that can benefit from the data.

Advantages

• High read and write transaction rate

Disadvantages

• Not a very good design

RAID level 4

Unlike other RAIDS the disk striping happens in a different way where it takes the byte level rather than bit level. Minimum of 3 disks required for implementation

Advantages

• High rate of read transaction
• Aggregation of the Read transfer is rate is very high
• Efficiency is high

Disadvantages

• Design is complex
• Not a good write transaction
• If a disk fails, its hard to rebuild the lost data

RAID level 5

RAID 5 is the most secured RAID and it requires 3 drives but can also work with 16 and the data blocks are striped on the drive and are all parity checksum and data is being written on it. Although the parity data is not written to a fixed drive, but then it is distributed all over the drives and by using parity data the computer can recalculate data from some other blocks if the data is no longer available. So, in other words this can be also be said that the RAID 5 can be supported a single disk failure without losing any data. Moreover, cache memories are being implemented on to these drives to make their writing speed improve.

Advantages of RAID 5

• Data transaction for read is very good. For example – it reads the data so quickly
• Aggregation of data is good

Disadvantages of RAID 5

• The design of this RAID is complicated
• If a disk or drive fails, its hard to retain the data
• Transfer rate of the data is the same as single disk which is one of the main disadvantage

RAID level 6

This is RAID 6 is somewhat like RAID 5. In this drive the parity data are being written on both the drives. RAID 6 requires 4 drivers and can handle 2 drives losing. And thee is a very less chance of losing 2 drives at the same time. RAID 6 can survive even if it fails twice unlike like RAID 5 it doesn’t take a lot of time to rebuild the lost data

Advantages of RAID 6

• This is like RAID 5 where it reads and writes the data very quickly
• Even if two drives fail, there is a possibility of getting the failed drives data by replacing it with the new drive

Disadvantages of RAID 6

• Writing data are slower compared to RAID 5
• This drive is a bit complicated where rebuilding a drive can take time.
• Transaction of the data are slow because of the parity which does the calculation

RAID level 10

This RAID is identified as the nested RAID or even hybrid. The security is provided by mirroring all data from the secondary drives and by using striping across each of the drives to make the data transfer to high speed. And in this level, it requires at least four disk and the data will be striped and mirrored in pairs.

Advantages of RAID 10

• This RAID is implemented as striped arrays
• Fault tolerance
• RAID 10 has I/O rates.

Disadvantages of RAID 10

• Expensive
• Limited scalability

Selecting RAID 10 as security and redundancy where to help avoid the sacrifice of the data

I would personally use RAID 10 to obtain the maximum redundancy and security among the other RAID levels. This RAID level also gives the best performance with considerable speed of access to data. It is more redundant than other RAID levels because it stripes data across mirrored pairs. It is also the most secure RAID array because even if one of the disks fail the data can be recovered in no time due to it’s rebuild speed.

REFERENCES

Disadvantages Of Redundant Array Of Independent Disks. (n.d.). Retrieved January 22, 2017, from http://www.whatisnetworking.net/tag/disadvantages-of-redundant-array-of-independent-disks/

Lynn, S. (2014, March 27). RAID Levels Explained. Retrieved January 22, 2017, from http://www.pcmag.com/article2/0,2817,2370235,00.asp

RAID. (n.d.). Retrieved January 22, 2017, from https://www.prepressure.com/library/technology/raid

RAID Levels – RAID 3 – RAID LEVEL 3: Parallel Transfer With Parity. (n.d.). Retrieved January 22, 2017, from http://www.acnc.com/raidedu/3

Redundant Arrays of Inexpensive Disks – RAID 0-1-2-3 (Continued). (n.d.). Retrieved January 22, 2017, from http://www.datarecovery.net/articles/raid-levels-0-1-2-3.aspx