What is RAID? Who needs RAID? RAID, an acronym for redundant array of independent disks or also known as redundant array of inexpensive disks, is a technology that allows high levels of storage reliability from low-cost and less reliable PC-class disk-drive components, via the technique of arranging the devices into arrays for redundancy.
There are two key functions in RAID:
Mirroring: Data backup or Data preservation. Mirroring is the writing of identical data to more than one disk, known as RAID 1.
Striping: Data saving acceleration. Striping is the splitting of data across more than one disk, known as RAID 0.
RAID Levels
There are many different types of RAID standardized levels, most commonly use are RAID 0, RAID 1, RAID 0+1 (or RAID 1+0, or RAID 10), RAID 5, RAID 5+0 (or RAID 50), RAID 6, and RAID 60 (or RAID 6+0). Also less commonly use RAID standardized levels are RAID 2, RAID 3, and RAID 4.
There are also some non-standard RAID levels, the one that most common know is JBOD mode.
RAID 0:
|
Types |
Specification |
|
Striping |
ˇ |
|
Mirroring |
ㄨ |
|
Minimum HDD required |
2 |
|
Minimum HDD error support |
0 |
|
Data recover function |
Not support |
|
Pro |
Data transfer in higher speed |
|
Con |
Not support data recover. Potential to lose data |
|
* ˇ: support ㄨ: not support |
RAID 1:
|
Types |
Specification |
|
Striping |
ㄨ |
|
Mirroring |
ˇ |
|
Minimum HDD required |
2 |
|
Minimum HDD error support |
1 |
|
Data recover function |
Full Data recover support |
|
Pro |
Can still function when either one of the HDD broken. |
|
Con |
Needs at least one HDD for Data backup |
|
* ˇ: support ㄨ: not support |
RAID 0+1:
|
Types |
Specification |
|
Striping |
ˇ |
|
Mirroring |
ˇ |
|
Minimum HDD required |
4 |
|
Minimum HDD error support |
1 |
|
Data recover function |
Full Data recover support |
|
Pro |
Supports both Striping and Mirroring |
|
Con |
Needs more HDD |
|
* ˇ: support ㄨ: not support |
RAID 2:
|
Types |
Specification |
|
Striping |
ˇ |
|
Mirroring |
ˇ |
|
Minimum HDD required |
Depending by the Byte of data |
|
Minimum HDD error support |
0 |
|
Data recover function |
Recover by Byte |
|
Pro |
Supports both Striping and Mirroring |
|
Con |
Partial HDD space required for debug Complex Data coding process |
|
* ˇ: support ㄨ: not support |
RAID 3:
|
Types |
Specification |
|
Striping |
ˇ |
|
Mirroring |
ˇ |
|
Minimum HDD required |
3 |
|
Minimum HDD error support |
1 |
|
Data recover function |
Providing Data recover per HDD |
|
Pro |
Supports both Striping and Mirroring |
|
Con |
Parity Check will cause low efficiency in data storage |
|
* ˇ: support ㄨ: not support |
RAID 4:
|
Types |
Specification |
|
Striping |
ˇ |
|
Mirroring |
ˇ |
|
Minimum HDD required |
3 |
|
Minimum HDD error support |
1 |
|
Data recover function |
Providing Data recover per HDD |
|
Pro |
Supports both Striping and Mirroring while also supports multiple data reading |
|
Con |
High HDD physical damage, Parity Check will cause low efficiency in data storage |
|
* ˇ: support ㄨ: not support |
RAID 5:
|
Types |
Specification |
|
Striping |
ˇ |
|
Mirroring |
ˇ |
|
Minimum HDD required |
3 |
|
Minimum HDD error support |
1 |
|
Data recover function |
Providing Data recover per HDD |
|
Pro |
Supports both Striping and Mirroring while also supports multiple data reading |
|
Con |
Takes longer for Data recovery |
|
* ˇ: support ㄨ: not support |
RAID 6:
|
Types |
Specification |
|
Striping |
ˇ |
|
Mirroring |
ˇ |
|
Minimum HDD required |
4 |
|
Minimum HDD error support |
2 |
|
Data recover function |
Provides data recovery for every two HDD |
|
Pro |
Supports Striping function |
|
Con |
Requires many HHD to support |
|
* ˇ: support ㄨ: not support |
JBOD:
|
Types |
Specification |
|
Striping |
ㄨ |
|
Mirroring |
ㄨ |
|
Minimum HDD required |
2 |
|
Minimum HDD error support |
0 |
|
Data recover function |
Not Support |
|
Pro |
Combines multiple HDD into one large Storage |
|
Con |
Single HDD error will cause the JBOD combine storage error, will require mirroring support
JBOD will require setting at initial stage, unable to add any HDD in the future. |
|
* ˇ: support ㄨ: not support |
RAID quick comparison: