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RAIDRedundant Array of Independent Disks

Raid was previously know as ‘Redundant Array of Inexpensive Disks’ but now the abbreviation stands of ‘Redundant Array of Independent Disks’. The redundancy is in the multiplicity of disks all of which work together as one single logical volume. RAID enables web hosts to use multiple storage drives together as if they were a single storage, it spreads the data evenly across each of the drives resulting in faster performance, higher capacity, and redundancy.

Its storage visualization techniques that enables improved reliability, performance, and capacity of system by using multiple physical storage drives. Copying data is referred to as mirroring or striping data across the disk drives so that in the case of whole disk failure or device read errors, different levels of raid can provide a solution for such data loss.

Striping and mirroring is the storage technique that gives RAID its redundancy, depending on the raid type any one of the disks can completely fail without any loss of data.
Striping and parity is either done on host server’s OS or in the storage array controller. The distribution of data across the drives varies as per required redundancy and performance and these different schemes or data distribution layouts are referred to as RAID levels, represented by numbers such as RAID 0, 1, 5, and 10 that are each a combination of mirroring and/or striping. To provide even more advantage nested or hybrid RAIDs exist such as RAID 0+1 and RAID 1+0 that have multiple copies of data using various techniques.

Software RAID

There are many operating systems that have a few built-in features and server OS that support RAID configuration. Software RAID is done through the devices motherboard or operating system. Software RAID through the motherboard BIOS is very uncommon with server hosts as it can slow down the system due to the overheads, and most motherboard RAID don't support the higher levels that many server hosts require.

Operating system RAID is uncommon with production windows systems, and some linux host; however it's becoming more common due to some modern RAID levels only being available on software. FreeNAS being one of the operating systems that support modern RAID algorithms that are not available with hardware RAIDs.

Hardware RAID

Hardware RAID processes on a discrete controller at either the server or at the level of the storage subsystem. There is a reduced load on the server processor and generally faster performance. Hardware RAID controllers accommodate advanced features such as drives being hot-swappable (ejected and changed without shutting down the server).

Hardware RAID is more expensive than software RAID but offers better performance and interoperability. The software comes at a lower price but has limitations that hardware can easily beat.

RAID has become an essential tool and practice for web hosts that require the ability to replace faulty hardware without having to power down the system, who require complete data redundancy, and need high performance storage.