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RAID Builder (find your RAID solution)
1. 2. Show RAID options

Host Controller Types

Software

A software based RAID system is based entirely at the operating system level. The RAID software layer sits above the device drivers and provides the link from physical drive to logical drive. The physical drive would be the actual piece of hardware while the logical drive would be the drive visible to the end user on the computer. In other words, the RAID software makes multiple physical drives show up as a single logical volume/ drive.

Software RAID systems are very cost effective and easy to implement, but are not as efficient as other RAID system types. This is due to software RAID systems being entirely dependent on the host system's (your computer) resources and CPU overhead for usage. Most modern OS's (including OS X) have RAID capabilities built in with the most common being RAID 0, 1, 0+1. Some include additional capabilities for RAID 5.

Hardware (Firmware/Driver Based)

A firmware based RAID system is often somewhat mistakenly known as a hardware system. Designed to solve some of the shortcomings of Software based RAID systems and be less expensive than hardware systems, firmware based systems were designed to fill the gap. These are often referred to as "RAID Controllers" though they do not have any sort of actual RAID controller within them, but are often standard disk controller chips with special firmware and drivers. The burden of the RAID calculations fall upon the host system's resources and CPU overhead.

In a firmware based RAID system, the RAID instructions are stored in the firmware of the device (for example the bridge board of the OWC Mercury Elite Dual Bay units & GMAX units). During startup/boot, the RAID is essentially kick-started by the firmware and kept in that state until the host (computer) OS is ready to handle the actual use of the drives and RAID calculations at which point the device drivers are used.

True/Full Hardware

A hardware based RAID system is the best way to implement RAID. All of the RAID functions are performed by dedicated hardware (processor, memory, & operating system) referred to as a "RAID Controller". Unlike a firmware/driver system being referred to as a "RAID Controller", a hardware system is the true form as it actually does control the RAID functions.

A hardware RAID system potentially offers the best performance, but it is dependent upon the hardware the system itself uses. Because all of the RAID functions are self-contained within the RAID controller, there are virtually no resources used from the host computer system. While potentially the most efficient, hardware RAID systems are also the most expensive to implement.

  • Definitions:
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RAID 0 (Stripe)
Data is split into blocks over two or more drives at same time for high speed and large capacity.
Capacity
blue meter 4
Data Safety
orange meter 1
Performance
green meter 4
RAID 1 (Mirror)
Data is written at same time to two drives only for highest level of data safety and redundancy.
Capacity
blue meter 1
Data Safety
orange meter 4
Performance
green meter 14
RAID 10 (1+0)
Data is Striped (RAID 0) over two Mirrored sets (RAID 1) of drives for fast redundancy.
Capacity
blue meter 2
Data Safety
orange meter 4
Performance
green meter 2
RAID 5 (Stripe with Parity)
Data is Striped (RAID 0) while incorporating parity over three or more drives for the best combination of speed, capacity, and redundancy.
Capacity
blue meter 3
Data Safety
orange meter 3
Performance
green meter 3
JBOD
(Just a Bunch Of Disks/Drives)
Each disk shows up as an individual logical volume on the computer. A 4 bay unit populated with drives will have 4 logical drives show up on the computer.
Capacity
blue meter 4
Data Safety
orange meter 1.5
Performance
green meter 1
Span (N-RAID)
Combines capacity of two or more drives of varying size without any RAID data distribution scheme into one logical desktop volume.
Capacity
blue meter 4
Data Safety
orange meter 1.5
Performance
green meter 1