Labels:text | screenshot | letter OCR: RAID 3 AND RAID 4 Logical sector 1 Logical sector 2 Logical sector 3 Controller Date from server Logical sector 4 Parity block Figure 5: An illustration of RAID levels 3 and 4. Each of the drives (1 through n-1, in this case n-5) is accessed in a stripe set; the last drive is dedicated to storing the parity data. The famnetional distinction between RAID levels 3 and 4 is that RAID 3 addresses each drive at a byte level, while level 4 addresses the drives at a block level. Note that in both cases only one write operation can occur at a time because of the dedicated parity drive: in RAID 3, only one. read operation can occur at'a time because one logical block is spread across each drive.
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