Redundant Array of Independent Disks (RAID) takes multiple disk drives and creates arrays that are resilient and highly available by mirroring and striping data across them. It also builds in the means to recover from disk failure using parity data.
The different ways that mirroring, striping and parity are used defines the different RAID levels. Processing is required to carry out those actions, and that can take place on the host server’s OS or in the storage array or controller. This is also called Hardware RAID vs Software RAID.
With Hardware RAID, the processing work is done on a controller card located in the system. This avoids added load on the system’s processor or buses and allows for advanced features such a higher levels of RAID configuration and the addition of a spare pool, in case of failure. Hardware RAID, because of the additional controller card, tends to be more expensive then software RAID. Hardware RAID can be found on the BNAS line of systems.
Software RAID uses disks attached directly to the system and the processing power of the motherboard to create the RAID. All you need to do is connect the drives and configure the RAID level you want. Because the processing for the RAID is carried out on the motherboard, this could slow down the RAID calculations and other operations that are carried out on the system.
RAID 0 and RAID 1 place the lowest overhead on software RAID but adding the parity calculations present in other RAID levels is likely to create a bigger impact on performance. Software RAID can be found on the NetSwap line of our products.
Software replication is the act of taking the data off one disk and copying it to another. Unlike RAID, there is no parity or striping and no built-in failure protections found in certain RAID configurations. It is a cost-effective solution with a high degree of flexibility, depending on needs. Because it is software based, once again the load will be placed on the processor and its buses. However, because there are not necessarily calculations involved, it is a much lower impact on the system than RAID. Software replication can be found on our RNAS line of products via our High-Sync software.