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Contemporary disc systems of RAID

the concept of redundant arrays of low-cost drives, Redundant Arrays of Inexpensive Disks (RAID), and describe the basic configuration of RAID (levels). There are three main trait RAID- arrays: set physical disks from a user's perspective is a single virtual disk large capacity; - distributed data on recruitment drives; in recruiting there Abundant capacity, providing an opportunity to recover data when there is a failure of one or more disks. RAID Level determined by way of distribution and use of redundant tanks way. Of the five RAID- levels, as described in the article, levels of 1.3 and 5 encountered considerable interest in the industry. In addition, two more have been proposed RAID- level: 0 and 6. Consider the features RAID levels. Let conditionally consider that RAID- array is a set of physical disks only connected to the computer, and does not contain any additional logic than the minimum necessary to ensure data exchange. RAID-0. RAID-0 is not redundant capacity. The failure of any drive leads to the impossibility of access to the data and can lead to a loss. (Formally, it should not be used for this configuration symbol RAID-0. perhaps correct to refer to it as RAID-0). The distribution of data is carried out on physical disks to read. The cumulative memory space is divided into segments of equal length. Designate these segments of the letters A, B, C, etc. Segment A physically located on the first drive, V-segment on the second disc in the same location as the first A, C-segment in the third, and the segment 0-for the fourth. The fifth segment is placed again on the first drive after the segment A, sixth in the second segment, followed by B, and so on until all seggmenty not be distributed in all physical disks. Performance data distribution will vary depending on the ratio of size and length of the segment-read / write file. First, the size of a large segment relative to the size of the file. In his small portion (shaded). When recording or reading only recourse to this part of the segment in the second drive. Most queries such ratio to the size of the file size segment will relate to a single segment. When reading data virtual address into a physical address is displayed segment on the disk containing the data. The data read from the segment. Similar actions implemented and with the record. Since then almost every request would be consistent with the only segment, multiple disks in the array will be able to serve different requests in parallel. This ensures good performance of requests for small and medium sized.
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