RAID, an acronym for Redundant Array of Independent Disks, is a technology that provides increased storage functions and reliability through redundancy, combining multiple disk drives components into a logical unit where all drives in the array are interdependent.
Different levels of RAID:
RAID 5 is better suited for mostly read-oriented applications while RAID 0+1 is also better suited for write intensive applications. In addition, stripping component (RAID 0) of RAID 0+1 offers the same read performance as RAID 5.
In our case for CRM application’s database, where we had to ensure good read-write speed with data protection, we chose RAID 1 for 2 drives (500 GB SATA) in Dell PowerEdge 6850 server and for a sports portal we used RAID 10 in Dell PowerEdge M600 server and for a Bank database I had RAID 10 with remote mirroring in IBM Power System.
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Different levels of RAID:
- RAID 0 – Block level striping without mirroring
- RAID 1 - Mirroring without striping
- RAID 2 - Bit-level striping with dedicated Hamming-code parity.
- RAID 3 - Byte striping with dedicated parity drive
- RAID 4 - Block striping with dedicated parity
- RAID 5 - Block striping with distributed parity
- RAID 6 - Block striping with double distributed parity
Level | Advantages | Disadvantages |
RAID 0 | Fastest I/O No overhead for parity Simple design, easily implemented | Not really RAID One drive failure destroys all data Not for mission-critical deployment |
RAID 1 | All drives usable for data reads Can be implemented w/ 2 drives | Greatest storage overhead - 100% Highest cost/capacity ratio |
RAID 3 | High transfer rates Degraded mode still fast | Requires spindle synchronization Can't do overlapped I/O |
RAID 4 | High read transfer rates Efficient use of capacity | Poor write rates Parity drive can be bottleneck |
RAID 5 | Very high read rate Efficient use of capacity | Slower write rates Slow rebuild times |
RAID 6 | Allows failure of multiple drives | Very poor write performance Proprietary solution, rare |
RAID 7 | Supposed to be fastest | Proprietary, very expensive |
RAID 1+0 | Very high reads and writes | Most expensive |
RAID for databases:
There are a number of factors to consider when choosing the appropriate RAID level for a specific application’s data storage.RAID 5 is better suited for mostly read-oriented applications while RAID 0+1 is also better suited for write intensive applications. In addition, stripping component (RAID 0) of RAID 0+1 offers the same read performance as RAID 5.
In our case for CRM application’s database, where we had to ensure good read-write speed with data protection, we chose RAID 1 for 2 drives (500 GB SATA) in Dell PowerEdge 6850 server and for a sports portal we used RAID 10 in Dell PowerEdge M600 server and for a Bank database I had RAID 10 with remote mirroring in IBM Power System.
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