Guide to RAID(Part III/III)
The ability to make choices based on facts and analysis, has always been a challenge for a person managing IT infrastructure. Much of this hardship can be attributed to the day to day advances in technology, and stiff markets.
Out here, we help to make one such choice – that of choosing Hardware or Software RAID. Earlier we ventured into basic concepts of RAID and comparison of various RAID levels. Here we describe and compare hardware and software RAID solutions.
Definition of Software and Hardware RAID
To put it simple, a RAID solution that uses the Host’s CPU resource, and is implemented as a software that runs within the host’s O/S is termed as Software RAID. While, a setup wherein dedicated hardware in the form of “RAID controller” is used to control the RAID array, is referred to as Hardware RAID.
Advantages of Software RAID
- Software RAID solutions can distribute data across various drive technologies such as IDE, ATA, SCSI, iSCSI, or any other network/block device. This is obtained by the high level of abstraction prevailing in software RAID implementations.
- Being hardware controller less, disks can be easily moved between arrays/controllers, unlike a hardware controller driven state, where such movements would be restricted.
- These days with multi core environments, CPU cycles are no more a big concern. If you have free resources, you could use it, rather than relying on a less powerful dedicated processor that accompanies the hardware RAID.
- The solution is feature rich, and newer features usually comes in along with the O/S package updates. Unlike hardware RAID, you do not have to worry about the varying complexity of the management interfaces, outdated firmware and cease of support for a given RAID card.
Advantages of Hardware RAID
- The ability to manage disk drives across multiple O/S and file-systems. Independent of the host O/S’s integrity. And the array can house the boot partition of OS unlike software RAID solutions that typically cannot boot off a software RAID array.
- Advanced RAID features like disk hot plug, easy array migration and online expansion etc.
- In built caching to reduce access times, and ability to use write-back caching with battery backed memory state protection.
- Fine tuned software and powerful GUI for maintenance of the RAID array, all without using the host’s resources.
There is probably no solution that suits all your requirements, and hence the adoption of a solution is usually a trade-off between requirements. The in depth know how of the requirement and options, is what helps in implementing a solution!
More on RAID array monitoring to follow…
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