Home | Contents | Help   Raidhelp     The RAID Controller It is important that you understand and have already selected the RAID Level or Levels you will use before you purchase any RAID Controller as not all controllers will offer the option of creating an array in all possible levels. Most controllers do offer the same most popular RAID levels such as RAID Level 0 (some offer variations on it such as Level 1/0), Level 1 to create a simple mirrored pair, and Level 5, as part of their basic support. However, the fact that these three levels have become the most popular makes many engineers and users assume one of these levels is suitable and largely ignore other RAID Level options. The three levels mentioned above have simply become the most popular because they offer the best compatibility & flexibility across different data types and environments. Manufacturers can therefore simplify their controller design. A controller that supports every possible RAID Level is uncommon and will invariably be expensive. You should carefully study all the RAID levels, select the most appropriate, and purchase a controller that offers all the functions you will need now and in the future. RAID Controllers come in a variety of guises or types. The three main categories can be summarised as follows: Independent Hardware Controllers PCI-based Controllers Software RAID Programmes Once you have selected your RAID Level or Levels, you need to select the type of controller that offers the support that meets these specifications. Once that is done, you will then need to select an individual controller that meets your list of requirements. The more effort and time spent considering the options, the more suitable the RAID controller will be for your environment.  Unlike many other products, it is important to select a controller by functions and support rather than by simply selecting a large manufacturer that produces high-level storage or systems in other areas. To a certain extent it is necessary to largely ignore the size or popularity of the manufacturer in other areas of the market. RAID controllers are highly specialised products and the best RAID controllers on the market are built by specialist RAID companies. Most major manufacturers do produce RAID controllers and array systems, but they tend to be rather limited in range, and are sometimes not usually of the same high-level functionality as specialist products from dedicated RAID manufacturing companies.  To confuse the issue even further, many manufacturers (even very large well-known ones) use controllers built by one of these specialist companies and integrate them into their own systems under their own brand-name. For example, Infortrend hardware RAID controllers can be found in many RAID systems all with completely different brand-names on the casing. The specialist nature of RAID controller development leads many manufacturers to purchase the technology from third-party specialists.  The difficulties and problems surrounding RAID controller development can be clearly illustrated by Adaptec, the undisputed market leader in SCSI products, who dropped their range of hardware controllers before they even really marketed them. This was due to a number of factors surrounding the delayed development. These hardware controllers were intended to supplement their range of AAA13x series of PCI-based RAID controllers for NT and NetWare, which offer very good value and stability for this level and type of system. Adaptec eventually sold their hardware RAID controller division to concentrate on improving these existing products, which is rather a shame as the specifications for these controllers carried high expectations. An overview of each category are given in the next section. Related topics: Components: Controller Categories Components: Enclosures Components: Logical Drives & Volumes Components: Physical Storage Media SAFTE Redundant Controllers   Raidhelp   RAIDhelp© Copyright 1999-2004 Antony Kershaw