RAID Technology has become the standard for servers and networks requiring increased speed or reliability over a standard hard drive. Micro Technologies is now featuring RAID controllers and equipment to implement with your existing or new server. From Serial Attached Scusi (SAS) to ATA, and from software and controllers to drives, Micro Technologies has your needs covered.

What do the different RAID levels offer me?
RAID 0 | RAID 1 | RAID 4 | RAID 5 | RAID 10 | RAID 50

RAID 0

Also known as disk striping. With RAID 0, data is written (striped) in sequential sectors across multiple (more than two) drives. In the most basic, two drive configuration, half the data would be stored on each drive with no duplication. RAID 0 offers little protection for data because there is no redundancy (duplication) of the data, so if one drive fails the entire array will stop working. RAID 0 increases performance dramatically as information can be written or retrieved by several drives at once, minimizing the overall seek time of larger files. Unlike other RAID formats, the full capacity of all the drives can be used for storing data so two 100Mb drives in a RAID 0 array will give the user 200Mb of useable space.

RAID 1

Also known as drive mirroring. With RAID 1, identical drives are "mirrored" so that as data is written to one drive, the controller copies identical data to a second drive. Mirroring delivers excellent data protection because if either drive fails, the RAID controller will automatically drop back to using just the remaining good drive which has a full copy of the data. The downside of RAID 1 is the relatively high price which results from the 100% duplication which means half of your total drive capacity is lost. If you have two 100Mb drives in your array, only 100Mb of space is available to the user. However, there is little or no overhead in retrieving data off of a mirrored cache drive when the main drive is also accessible, so RAID 1 delivers good performance in a degraded drive scenario.

RAID 4

With RAID 4 data is striped at a block level across several drives, with parity stored on one drive. The parity information allows recovery from the failure of a single drive. The performance of RAID 4 is very good for reads. Writes, however, require that parity data be upgraded each time. This slows down random writes, in particular, though large writes or sequential writes are fairly fast.

RAID 5

RAID 5 is the most popular implementation of RAID because it allows customers to deliver excellent data protection and good performance with only a small amount of overhead for parity. RAID 5 employs data striping, as well as writing parity information, but instead of using a single drive to hold all of the parity information like RAID 4, RAID 5 distributes the parity information. As data is striped across all drives, parity is also being striped. Because the parity is being distributed instead of being held in a single drive, performance is enhanced. In any RAID 5 array, one drive capacity is dedicated to the parity; the larger the array, the lower the overhead of storage space. For instance, in a three-drive array (the minimum number of drives required to run under RAID 5), one drive's total capacity is consumed by parity information (33% of total capacity), and in a ten-drive array, one drive is consumed by parity (10% of total capacity). As you can see the storage capacity overhead decreases as the array increases.

RAID 10

A combination of RAID 0 and RAID 1, data is distributed across multiple drives without parity, and then the entire array is mirrored. Although this delivers good performance, the drive storage overhead is 50% because you are mirroring the data.

RAID 50

A combination of RAID-5 and RAID-0. This configuration stripes data with parity across each RAID-5 subset of disks. Each RAID-5 subset requires three hard disks. RAID-50 provides a higher degree of fault tolerance since one disk per subset may fail without data loss. Since the parity bits are distributed across the RAID-5 subsets, data rebuild speed is increased. Advantages: Greater degree of fault tolerance and potential for faster data read rates. Things to consider: Disk failure impacts throughput and reconstruction of information after a disk failure takes longer than with a mirrored solution.

RAID | Serial Attached SCUSI (SAS) and SATA

LSI/3ware | Adaptec

What do the different RAID levels offer?

• RAID 0 - Data striping with no redundancy - increased performance with read/write procedures
• RAID 1 - Data mirroring without striping - offers excellent data protection, only 50% space efficency
• RAID 5 - Data striping with parity - Most common implementation, offers data protection and performance. Storage efficiency is higher as more drives are implemented into the array.
• RAID 10 - Data striping and mirroring - This implementation combines the strengths and weaknesses of RAID 1 and RAID 0. Although it offers good preformance the storage efficiency is only 50%
• RAID 50 - Data striping with parity across Disk subsets - Offers a higher degree of fault tolerance and Data rebuild speed is increased. Disk failures do take longer to restore than with a mirrored solution.

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