RAID meaning

RAID 

• RAID stands for Random Arrays of independent disks.
• The storage which we are used in laptops,computers are single disk.but its servers,data centers,we used multiple disks, means RAID technology.
• RAID saves data in the form of cache can improve system performance in the same way additional disks can also improve system performance.
• In RAID we use array of disks.These disks operate independently.
• Since,there are many disks,separate and multiple input-output request can be handled in parallel if the data required is on separate disk.
• A single input-output operation can be handled in parallel if the data required is distributed across multiple disks.

Benefits of RAID

1. RAID technology presents data loss due to disk failure.
2. RAID technology can be implemented in hardware or software.
3. Servers may be use of RAID technology.
4. To present fail of operating system,RAID technology is beneficial.

Levels of RAID
RAID 0:
                                

RAID 0 implementation requires two disks.There is no redundance in RAID 0.RAID level 0 divides the data into block units write.As data is placed across multiple disk it is also called data striping.This is no parity checking of data.A parity check is the processing which accurate data transmission between notes during communication is checked.So if data in one drive gets corrupted them all the data would be lost. This RAID 0 does not support data server.

RAID 1:

The other name of RAID 1 is mirroring,as it copies data on two disk drive simultaneously.Minimum two or more hard disk are required.
As same data is placed on multiple disk it is called data mirroring. No striping is used only mirroring is used.A write request means that both the disk must updated.this can be clone is parallel 
Recovery from failure is simple if one drive fail we just have to access data from the second drive

RAID 2:

In this RAID 2 all disk participate in the execution of every input-output request.Individual disk drives are synchronized.Data striping is used.Error correcting code is also calculate and stored with data.RAID 2 is not implemented in practice due high costs.

RAID 3:

In this RAID we required minimum three disks.It performs byte level striping with dedicated parity.All disk can be accessed in parallel.In case of disk failure the parity drive is access and data is reconstructed from the remaining devices.Once the fail drive is replaced the missing data can be restored on the new drive.

RAID 4:

In Level 4 parity is transfer level. As with Level 3, a single drive is used to store redundant data using a parity check byte for each data stripe.