< Day Day Up > |
7.4. RAID 0 Disk StripingRAID 0 is not fault tolerant and is often used in situations that are not mission-critical, where performance and capacity are more important than uptime. RAID 0 is the only non-fault-tolerant RAID level supported by HP. RAID 0 is illustrated in Figure 7-4. Figure 7-4. RAID 0.RAID 0 is known as stripe sets because data is striped, or distributed, across all the drives in the array. Instead of filling each drive to capacity in sequential order, only a small amount of data, called a block or a chunk, is stored on each drive before allocation advances to the next drive. The size of each block (chunk size) is called the striping factor and the collection of blocks at the same location on each physical drive is called a stripe. Data is broken into stripes (or chunks) and then written across multiple disks, greatly improving the disk latency (the time a disk head has to wait for the target sector to move under the head). In addition, 100% of the disk space is available for data and overall disk performance is improved. By definition, RAID 0 requires two or more drives for a true stripe set. However, with Smart Array controllers, a RAID 0 logical volume can be created with a single drive. Because RAID 0 has no overhead associated with duplication of information, it provides the highest performance. Both read and write requests can use all member disks simultaneously. The limitations of RAID 0 include the following:
|
< Day Day Up > |