[raid combo number five] SUPERSIZED! I By Evan Kamlet 52 <strong>Ping</strong>! <strong>Zine</strong> <strong>Magazine</strong>
It is apparent that the web hosting industry these days is all about reliability, speed, and price. Your potential clientèle will probably seek out the best of all three factors. RAID, or “Redundant Array of Independent/Inexpensive Disks”, is a technology that has existed for decades. In fact, IBM took out a patent for a storage system in 1978 that went on to be known as RAID in its adulthood. Today, most IT professionals in the hosting industry are familiar with it, but may not be aware of precisely how RAID can help reliability, enhance I/O speed, and even reduce costs when compared with more extravagant systems. Is RAID for you? There are an almost endless number of RAID levels, combinations, and options. Which should you choose? At its core, RAID works exactly as its acronym suggests -- it establishes a redundant array of (inexpensive) disks. With RAID, you create an array of two or more hard disk drives to add data redundancy (although it can also be used simply for I/O performance gains alone, but that’s no fun). And, with certain configurations, you can expect increased performance when the operating system reads from or writes to the array when compared with a single disk. It is critical to note that RAID should not be your only backup system. Daily, weekly, and monthly backups are essential components in addition to RAID. In some cases, when server uptime is not a huge factor, regular backups may be all that you need. When we have a client sign up for a self-managed server and request two drives in a RAID mirror, we will always recommend our network backup service, or at least come up with some alternative backup system. Personally, I would rather see them backup from one drive to another than rely solely on RAID 1. And, RAID 1 will happily mirror your newly root-compromised data right from one drive to the other, just as it will happily mirror certain kinds of file corruption, and even corruption caused by a physical problem on one of the drives! And, a RAID mirror does not care if you accidentally delete the wrong file and need it restored from yesterday. In summary: RAID’S ADVANTAGES ·A simple and inexpensive way to add redundancy to your data; ·Certain setups will allow for higher disk read and write performance; ·Many setups allow for the hot-swapping of a bad drive; ·There are many options to choose from that may suit your needs; ·Reduced server downtime in the event of a single, or multiple drive failure. RAID’S DISADVANTAGES ·RAID should not be considered a full backup system in ANY configuration; ·RAID is more expensive than using standalone drives; ·“Bare metal” data recovery from an array failure is more complicated than recovery from a standalone drive failure, although it is much less likely for the whole array to fail. HARDWARE OR SOFTWARE? The first option to consider is whether one wishes to use hardware or software RAID. Are you concerned about performance? If so, use hardware RAID. Software RAID is often acceptable for a simple RAID 1 mirror of two or more drives. Both Windows and Linux have software RAID capabilities. The difference between hardware and software is that your CPU will be handling the array synchronization on software RAID, which can reduce overall performance. In addition, if you try to install or use other operating systems with software RAID, they may not recognize the array. A hardware RAID add-on card typically runs from $150 to $400+ and can offload the data synchronization duties to itself rather than your CPU. RAID TYPES Although RAID setups can vary widely, generally they are based on some core “building blocks,” in the form of basic RAID setups. The following methods are generally used [continued]
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