RAID 3
| RAID 3 provides disk striping and complete data redundancy though a dedicated parity |
| drive. The stripe size must be 64 KB if RAID 3 is used. RAID 3 handles data at the block |
| level, not the byte level, so it is ideal for networks that often handle very large files, such |
| as graphic images. RAID 3 breaks up data into smaller blocks, calculates parity by |
| performing an |
| in the array. The parity data created during the |
| drive in the array. The size of each block is determined by the stripe size parameter, |
| which is set during the creation of the RAID set. |
| If a single drive fails, a RAID 3 array continues to operate in degraded mode. If the failed |
| drive is a data drive, writes will continue as normal, except no data is written to the failed |
| drive. Reads reconstruct the data on the failed drive by performing an |
| operation on the remaining data in the stripe and the parity for that stripe. If the failed |
| drive is a parity drive, writes will occur as normal, except no parity is written. Reads |
| retrieve data from the disks. |
Uses | Best suited for applications such as graphics, imaging, or |
| video that call for reading and writing huge, sequential |
| blocks of data. |
Strong Points | Provides data redundancy and high data transfer rates. |
Weak Points | The dedicated parity disk is a bottleneck with random I/O. |
Drives | Three to 15 |
Cont’d
Chapter 3 RAID Levels | 21 |