RAID (Redudnat Array of Independent Disks) is a way of storing the same data in different places on multiple hard disks to protect the data in case of hard ware failure. RAID works by placing data on multiple disks and allowing input/output (I/O) operations to improving performance,because the using of multiple disks increases the (MTBF) mean time between failures, storing data redundantly also increases fault tolerance.
RAID arrays appear to the operating system as a single logical hard disk, RAID has techniques of disk mirroring or disk striping.
Disk Mirroring: It copies identical data onto more than on drive
Disk Striping: It is process of dividing a data into blocks and spreading the data blocks across multiple storage devices.
On most situations you will be using one of the following levels of RAID’s
RAID 0:
Following are the key points to remember for RAID level 0.
- Minimum 2 disks.
- Excellent performance ( as blocks are striped ).
- No redundancy ( no mirror, no parity ).
- Don’t use this for any critical system
RAID 1:
Following are the key points to remember for RAID level 1.
- Minimum 2 disks.
- Good performance ( no striping. no parity ).
- Excellent redundancy ( as blocks are mirrored ).
RAID 5:
Following are the key points to remember for RAID level 5.
- Minimum 3 disks.
- Good performance ( as blocks are striped )
- Good redundancy ( distributed parity ).
- Best cost effective option providing both performance and redundancy. Use this for DB that is heavily read oriented. Write operations will be slow.
RAID 10:
RAID arrays appear to the operating system as a single logical hard disk, RAID has techniques of disk mirroring or disk striping.
Disk Mirroring: It copies identical data onto more than on drive
Disk Striping: It is process of dividing a data into blocks and spreading the data blocks across multiple storage devices.
On most situations you will be using one of the following levels of RAID’s
RAID 0:
Following are the key points to remember for RAID level 0.
- Minimum 2 disks.
- Excellent performance ( as blocks are striped ).
- No redundancy ( no mirror, no parity ).
- Don’t use this for any critical system
RAID 1:
Following are the key points to remember for RAID level 1.
- Minimum 2 disks.
- Good performance ( no striping. no parity ).
- Excellent redundancy ( as blocks are mirrored ).
RAID 5:
Following are the key points to remember for RAID level 5.
- Minimum 3 disks.
- Good performance ( as blocks are striped )
- Good redundancy ( distributed parity ).
- Best cost effective option providing both performance and redundancy. Use this for DB that is heavily read oriented. Write operations will be slow.
RAID 10:
Combining RAID 1 and RAID 0, this level is often referred to as RAID 10, which offers higher performance than RAID 1, but at a much higher cost. In RAID 1+0, the data is mirrored and the mirrors are striped.
Following are the key points to remember for RAID level 10.
- Minimum 4 disks.
- This is also called as “stripe of mirrors”
- Excellent redundancy ( as blocks are mirrored )
- Excellent performance ( as blocks are striped )
- If you can afford the dollar, this is the BEST option for any mission critical applications (especially databases).
