In this topic we will discuss about what is RAID and what are the level of RAID we are using in linux.
RAID AKA. Redundant Array Of Inexpensive/Independent Disk.
Lets discuses about the level of RAID available in linux.
RAID Level 0:
In this level of RAID data are split up in blocks that can be written upon (or) across all the drives in the array by using multiple disk (require atleast 2 disk) at the same time.
Advantage: RAID level 0 offers good read and write performance. Disadvantage: If one disk fails then the content in RAID level 0 array gets lost.
RAID Level 1:
Data are get stored twice by writing them to both to the data disk and the mirror disk. If a disk fails, the controller uses either data disk or the mirror disk for the recovery and continue its operations.
Advantage: It offer effective read & write operations. Disadvantage: The mail disadvantage is this kind of RAID level is little expensive because you are in need of two disk of same size.
RAID Level 3:
In this RAID concept the datablock are subdivided ie, striped and written on two or more disk. Where an additional no. of. dedicated drive stores the parity information. So totally in this level of RAID you are in need of 2 for data and 1 for parity information. Since Parity is available this RAID can withstand single disk failure.
Advantage: Provides high read and write performance for larger data transactions. Disadvantage: Performance will be slower when doing small i/o operations and can satisfy only one i/o operations at a time.
RAID Level 5:
This Level of RAID is commonly used one. It is exactly similar to the RAID level 3 as instead of having parity information in an independent disk it stores the parity information spread along all the disk. It requires 3 or more disk.
Advantage: Read Transation is very faster. Disadvantage: Write performance is poor as the parity calculation is done on the same disk where its writing the data.
