3Ware 9550SXU-16ML User Guide - Page 180

Chapter 9. Maintaining Units occurs. (For more information, see "Setting Background Task Rate" on page 175.) You can also postpone initialization until a scheduled time. (For details, see "Scheduling Background Tasks" on page 176). Note: Units that do not need to be immediately initialized for full performance will be automatically initialized using foreground initialization if they are ever verified. (Verification requires that the unit have been previously initialized.) This will not affect the data on the drives, and the units will perform normally, although performance will be slowed until the initialization and verification are completed. Initialization of Different RAID Types Information about initialization for each of the different RAID types is described below, and summarized in Table 9 on page 171. Initialization of RAID 0 Units RAID 0 units do not need to be initialized and are immediately available for use with full performance when created. Initialization of RAID 5 and RAID 50 Units Regardless of the size, all 9000-series RAID-5 and 50 arrays are fully fault tolerant upon creation. This is because these configurations use a specialized scheme for writing to the unit, which does not have to be valid to provide fault tolerance. Performance of RAID 5 units with 5 or more disks, and RAID 50 units with 2 subunits of 5 or 6 disks will improve after the unit has been initialized. For these configurations, initialization begins automatically after you create them. If you create them in the 3BM utility, zeroes are written to all unit members. If you create them through 3DM, RAID 5 parity is calculated and written to disk, keeping any data in the unit intact. RAID 5 units with 3 or 4 disks do not need to be initialized to have full performance upon creation. Similarly, RAID 50 units with a grouping of 3 or 4 do not need to be initialized, however RAID 50 with a grouping of 6 do need to be initialized for full performance. Initialization of RAID 1 and RAID 10 Units RAID 1 and RAID 10 units do not need to be initialized when they are created to be fault tolerant and are immediately available for use with full performance when created. 170 3ware 9550SX Serial ATA RAID Controller User Guide