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techsupport@risingedge.com
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Implementing RAID
RAID Architectures
RAID systems are typically implemented as one of three types; software,
internal hardware, or external hardware. Each implementation has its own advantages
and disadvantages. Following is a brief summary of the characteristics of each
architecture.
Software
Typically requires platform and operating system specific device drivers. Operates
with a set of disk drives connected to the host computer through a disk interface
adapter. Inherent low cost. Many operating systems have built in RAID or stripe set
capability. Many products offer data redundancy without hardware redundancy. Packaging of
the hardware is often left to the user and can not support hot swap components. Thus
system down time occurs in the event of a component failure. Configurations typically
limited to independent access arrays since all of the member drives are attached to the
same interface bus. Many OS RAIDs offer little if any data redundancy and are targeted
at improving storage subsystem performance.
Internal Hardware
Typically in the form of a RAID host adapter that fits into a bus slot of the
host computer. Attractively priced. Offer true multi-channel disk drive interfaces. No
burden on the host system CPU. Host computer system and operating system dependent. Host
interface cards are tied to the host bus architecture. Same packaging concerns as software
RAID.
External Hardware
Independent external controller that connects to the host computers disk
interface adapter and to the set of disk drives in the array subsystem. Offer true
multi-channel disk drive interfaces. No burden on the host system CPU. Unequaled fault
tolerance and data availability. Host and operating system independent device. Supports
redundant RAID controllers, power supplies, cooling fans, and multi-host interfaces. Hot
swap elements. Tend be the more expensive solution.
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