Using RAID

Using RAID

A vital tool for protecting a network’s data is the use of a Redundant Array of Inexpensive Disks (RAID). Using a RAID system enables you to set up the best disk array design to protect your system. A RAID system combines two or more disks to create a large virtual disk structure that enables you to store redundant copies of the data. In a disk array, the drives are coordinated into different levels of RAID, to which the controller card distributes the data.

RAID uses a format of splitting data among drives at the bit, byte, or block level. The term data striping refers to the capability of arranging data in different sequences across drives. Demonstrations of data striping are shown in Figure 9.3.

Your input in designing the most reliable drive setup for your network is an important responsibility. You must choose the best RAID implementation level to meet your users’ requirements in data integrity and cost. Seven levels of RAID are available on the market today: 0, 1, 2, 3, 4, 5, and 10. A higher number isn’t necessarily indicative of a better choice, so you must select the best level for your environment. The following paragraphs present a brief discussion of some of these available levels, notably RAID 0, 1, and 5, which Windows NT Server supports. Windows NT Workstation supports only RAID 0, and Windows 95 is not able to use any RAID levels at all.

A fault-tolerant disk scheme is used only to speed recovery time from a hardware fault. None of these RAID levels is intended to be a replacement for regular tape backups.

Further Information