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Learn about RAID

ALL ABOUT RAID CONTROLLER.

In late 1980 and early 1990, the provider of information technology services was faced with increasing a tremendous amount of stored data. The storage technology is becoming very expensive to put a large number of high-capacity hard drives on servers. RAID was born on the problem.

RAID is defined how? First RAID stands for Redundant Array of Inexpensive Disks (system backup disk). This is the operating system by connecting a series of low-cost drives together to form a single storage device with large capacity to support efficient and reliable than previous solutions here. RAID is used and the methods deployed in the enterprise storage and servers, but in 5 years RAID has become common for all users.

The advantage of RAID

There are three main reasons for the application of RAID:

Reserve
High efficiency
Low cost
The reserve is the most important factor in the development process for RAID server environment. Provision for memory backup if something goes wrong. If one drive in the array can become corrupted, it can convert to another hard drive without turning off the system or can use the backup hard drive. Preventive methods depend on the version of RAID is used.

When applying stronger RAID version you can clearly see its effectiveness increased. Effectiveness also depends on the number of hard drives linked together and the control circuit.

All managers of the IT group wanted to reduce costs. When RAID was born, the cost is a key issue. The goal of the RAID array is to provide better memory for the system compared with using separate disk drives with large capacity.

There are three levels of RAID to use desktop systems are RAID 0, RAID 1 and RAID 5. In many cases, only two of the three levels on the force and one of two techniques used was not a level of RAID.

RAID 0

RAID 0 really is not a valid RAID level. 0 level given level can not provide any backup for data storage. So if one drive fails, will endanger the data.

RAID 0 uses a technique called "striping." "Striping" split single block of data as shown in the drawings and spread them across the hard drive. The effect of striping is to enhance performance. Can record two blocks of data simultaneously to two hard drives, compared to a hard drive as before.

Below are examples of how data is written to RAID 0 how. Each line in the graph represents a data block and each column represents a different hard drive. The numbers in the table represents the data block. The same number indicates a block of data is repeated.

Hard drive 1
Hard Drive 2
Block 1
1
2
Block 2
3
4
Block 3
5
6
Therefore, if all six blocks of data in the tables combined into a single data file, you can read and write to your hard drive much faster than on a hard read. Each drive when operating in parallel can only read three volumes of data while it is necessary to use a single drive to read all six volumes of data. Limitations of this technique is that if one drive fails, data will not work. Need to access all six blocks of data can read data but can only access the 3 blocks.

Advantages:
Increase storage efficiency.
No loss of data storage.
Disadvantages:
No backup drive.
RAID 1

RAID 1 new version is the first true. RAID provides data redundancy method using simple techniques, "mirroring" (duplicate data). This technique required two separate hard drives have the same size. A hard drive is active, the rest is hard drive backup. When data is written to the hard work and it is also written to the backup drive.

These are examples of how data is written to RAID 1 like. Each line in the graph represents a data block and each column represents a different hard drive. The numbers in the table represents the data block. The same number indicates a block of data is repeated.

Hard drive 1
Hard Drive 2
Block 1
1
1
Block 2
2
2
Block 3
3
3
RAID 1 provides a version of the full data backup system. If one drive crashes, drive active rest. Limitations of this technique is the only RAID storage capacity of the two smallest hard drive if the storage capacity on two volumes can be used independently.

Advantages:
Provide comprehensive data backup.
Disadvantages:
Large storage capacity only by the smallest disk.
Not increase execution efficiency.
More time to change dies hard work when there are problems.
RAID 0 +1

This is a combination of RAID that some manufacturers have made to combine the benefits of the two versions together. This combination will only apply to systems with at least four hard drives. Techniques "mirroring" and "striping" together to create effective prevention. The first setting of the drive is activated and the data will be distributed through that second set will reflect these data to the second drive.

The following example shows that data is written to RAID 0 +1 how. Each line in the graph represents a data block and each column represents a different hard drive. The numbers in the table represents the data block. The same number indicates a block of data is repeated.

Hard drive 1
Hard Drive 2
Hard Drive 3
Hard Drive 4
Block 1
1
2
1
2
Block 2
3
4
3
4
Block 3
5
6
5
6
In this case, the data blocks will be distributed through the disk and is reflected between the two settings. Effective implementation of RAID 0 is increased because the hard drive only takes half the time compared to a single drive while ensuring redundancy. The main drawback of this approach is cost because it needs to have at least four hard drives.

Advantages:
Increase enforcement effectiveness.
The data is the entire reserve.
Disadvantages:
Require a large amount of hard drive.
The access data reduced by half.
10 or RAID 1 +0

Almost like RAID 10 RAID 0 +1. Instead of sharing data between the drive and set it reflects the first two drives mirrored together. This is a nested RAID setup. Two pairs of drives 1 and 2, 3 and 4 will reflect each other. Then they will be set to divide the sequence data.

Here is an example to show the data is written to RAID 10 How. Each line in the graph represents a data block and each column represents a different hard drive. The numbers in the table represents the data block. The same number indicates a block of data is repeated.

Hard drive 1
Hard Drive 2
Hard Drive 3
Hard Drive 4
Block 1
1
1
2
2
Block 2
3
3
4
4
Block 3
5
5
6
6
Also set as RAID 0 +1, RAID 10 requires a minimum of 4 drives to perform their functions. However, data is protected with RAID 10 RAID 0 +1 safer lot.

Advantages:
Increase enforcement effectiveness.
The data is the entire reserve.
Disadvantages:
Require a large amount of hard drive.
The access data reduced by half.
RAID 5

RAID 5 for the most powerful desktop systems. Characteristic of them is the need to have a hardware controller disk array management, but some computer operating systems can do this through software. This method uses divide "parity" (parity) to maintain data redundancy. Need at least three hard drives have higher capacity to apply the same RAID 5.

"Parity" is a binary math to compare two data blocks with a block of data based on two blocks of three things first. The easiest way to explain the odd and even. If the sum of two blocks of data bits is even, the number is even, if the sum of two blocks of data bits is odd, the number is odd. Thus operations are 0 +0 and 1 +1 +1 to 0 of 0 will equal 1 or 1 +0. Based on binary math, a drive malfunction is in the range will allow the bit "parity" to restore the data when it is hard to replace.

Here is an example shows that data is written to RAID 5 How. Each line in the graph represents a data block and each column represents a different hard drive. The numbers in the table represents the data block. The same number indicates a block of data is repeated. "P" bit is the "parity" for the two data blocks

Hard drive 1
Hard Drive 2
Hard Drive 3
Block 1
1
2
P
Block 2
3
P
4
Block 3
P
5
6
The bit "parity" between the rotating hard drive will increase performance and reliability data. Strip drives will increase efficiency through a single hard drive because the ability to burn more data faster than a drive. Data backup is also thanks to all the bits of "parity." Where the two drives fails, data can be recovered based on the data and the bits on two drives. Data storage is reduced by the parity data block. In fact, if n is the number of drives and z is the capacity, then we have the following formula:
(N-1) * z = Storage
In case 3 with a 500GB hard drive / drives, total capacity will be (3-1) = 1000 GB x500GB

Advantages:
Increased storage capacity
The data is the entire reserve
Ability to quickly swap 24x7
Disadvantages:
High price
Reduction in the effective implementation of the rehabilitation process
RAID software and hardware

To use RAID function, software must be installed on the operating system or through dedicated hardware to control the flow of data to move from computer hard drives. This is really important that RAID 5 has inherited a large amount of computer required to make appropriate calculations.

For software, the cycle of central processing unit (CPU) will execute the tasks necessary for RAID. Using software, the cost will be lower because all the necessary things are hard. The only problem with using software RAID which is a decrease system performance. Overall, the results can range from 5% or more depending on the processor, memory, hard drives and RAID types are put into use. Many people no longer use the software RAID controller RAID price of hardware has dropped in recent years.

Hardware RAID has the advantage of using dedicated circuits to control all the calculations for RAID in external processors. This method creates high-performance storage. RAID hardware problem is cost. Price controls for RAID 0 / 1 is very small by many "chipset" was built on the motherboard. Meanwhile, the hardware RAID 5 requires the vessels should have been added.

Hard drive options

Many people still do not know that the power and capacity of a RAID array depends very much on the hard drive is used. To achieve best results, all hard drives on the network should have the same style and brand. Besides, we also need to have the same size and similar performance. There is no requirement of consistency among the hard drive but if they can not uniformly affect the RAID array.

RAID's capacity depending on their level. For RAID 0, the division can be executed through the space of two drives. With two 80GB and 100GB drives, the output end of the range would be 160GB. Similarly, for RAID 1, the drive can only compare data in the smallest size so that the final capacity will only be 80GB. RAID 5 is more complicated than when calculated by the formula above. If you use 3 drives 80GB, 100GB and 120GB, the capacity will be 160GB of data.

Execution time of the sequence also depends on the hard drive. To execute a command function, then we have to wait for data to be written to each drive before you can continue to the next step. Mean graph of RAID arrays for example, the controller must wait until all data has been recorded in the first block across all drives in the array before you can continue up to another hard drive. Also means that in the range where a hard drive performance is only half will slow down the speed of other drives.

Conclusion

RAID support systems with many different utilities depending on the version used. Most customers will choose to use RAID 0 to boost performance without reducing the memory space. Mainly due to excess is not a major issue for the average user. In fact, most computer systems provide only RAID 0 or RAID 1. The cost to implement RAID 0 +1 or RAID 5 is too expensive for the average customer and can only be applied to the workstation or server system level.

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