RAID, the redundant array of inexpensive disks, first proposed more than 20 years ago as a better way to safely store data, is an idea that has won the hearts and minds of enterprise data storage professionals. RAID is everywhere. In essence, RAID has always promised to make data safer by not putting it all on one disk.In its most basic form, RAID allows disks to be arranged to protect the data that they contain by adding redundancy. In a properly configured RAID model, the loss of any single disk will not interfere with users' ability to access the data that is stored on them.
In this tutorial on RAID data storage for SMBs, learn about how RAID data protection is changing, how to choose the correct RAID level, and optimizing RAID storage for your business.RAID DATA STORAGE TUTORIAL TABLE OF CONTENTS
Roger Cox, research vice president at Gartner, said he sees three big trends starting to impact those thinking about purchasing RAID. One is the advent of various storage schemes that add bells and whistles to the RAID formula such as mirroring layered on top of a traditional striping of data. But few of the additions in spinning disk capability impress him as much as the potential for marrying solid-state storage to disk -- producing ultra-fast IO while retaining the more favorable cost structure of traditional RAID.
The second trend is cloud data storage and cloud data backup, which Cox predicts will see significantly more traction in 2010. For him, the cost and simplicity arguments make a lot of sense, meaning more and more companies will simply want to plug into storage located somewhere else, eliminating decision points about RAID purchases.
Third, there is the effort by vendors such as Cisco Systems Inc., Dell Inc., Fujitsu, Hewlett-Packard (HP) Co. and IBM Corp. to offer devices that provide server, storage and networking functionality in one integrated package. "They are trying to convince the user market that this is the way to simplify and reduce cost and complexity," he said.
When using RAID, there are many different options you should explore, including where to house RAID drives, whether to use software- or hardware-based RAID controllers, and what RAID level best fits your business needs.
The first issue to consider is where the RAID drives will be housed. Storage area networks (SANs) can house dozens (or more) drives, and provide high-performance RAID, but may be too costly for some SMBs. There are also other options available to house RAID drives: network-attached storage (NAS), external SATA boxes, or inside your computer.
Choosing the right RAID level for your SMB depends on performance, availability, capacity, economics and Quality of Service (QoS) or other service requirements. For an SMB environment, multiple RAID levels, similar to having multiple tiers or types of storage may be applicable. You need to look at your specific environment to find out what RAID level is right for you.
Although there are half a dozen or so officially recognized RAID levels, and a number of combinations, there are only a few that are commonly used in SMBs. For example, RAID 0 isn't really a RAID level at all because there's no redundancy. It is a shorthand way to describe striping data across several disks. It increases performance on reads and writes, but provides no additional protection against drive failure.
Some companies are moving beyond RAID to other methods of insuring disk reliability. Typically, these methods combine RAID features with proprietary methods of monitoring, managing, and repairing disks. Companies such as Atrato and Xiotech offer sealed arrays that are guaranteed up to three years (Atrato) or five years (Xiotech).
Atrato offers a Self maintaining Array of Independent Disks (SAID) in its Velocity 1000 product. This consists of 160 2.5-inch disks in a high-density 3U form factor enclosure, capable of supporting multiple independent data streams. Diagnostic and maintenance software is designed to automatically detect and correct problems, swapping in spare drives as needed.
For even more RAID news, tips and best practices in small business data storage, bookmark our small and midsized business storage hardware section.