Maintaining Units160 3ware SAS/SATA RAID Software User Guide, Version 9.5.1Initialization of Different RAID TypesInformation about initialization for each of the different RAID types isdescribed below and summarized in Table 12 on page 161.Initialization of RAID 0 UnitsRAID 0 units do not need to be initialized and cannot be initialized. RAID 0units are immediately available for use with full performance when created.Initialization of RAID 5, RAID 6, and RAID 50 UnitsRAID 5 units with three or four drives will be automatically initialized thefirst time they are verified.Regardless of the size, all 9000-series RAID 5, RAID 6, and RAID 50 unitsare fully fault tolerant upon creation. These configurations use a specializedscheme for writing to the unit, which does not have to be valid to provide faulttolerance.Performance of RAID 6, RAID 5 units with 5 or more disks, and RAID 50units with 2 subunits of 5 or 6 disks will improve after the unit has beeninitialized. For these configurations, initialization begins automatically afteryou create them. If you create them in 3BM using the default foregroundinitialization method, zeroes are written to all unit members before booting tothe operating system. If you create them through 3DM, you will boot to theoperating system and the RAID 5 parity is then 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 fullperformance upon creation. It is okay that 3 or 4 disk RAID 5 units are notinitialized. These RAID types are fully redundant, regardless of whether ornot they are initialized. Similarly, RAID 50 units with a grouping of 3 or 4disks in a subunit do not need to be initialized. However, RAID 50 with agrouping of 5 or more disks in a subunit do need to be initialized for fullperformance.Note: Units that do not need to be immediately initialized for full performance willbe automatically initialized using background initialization when they are verified forthe first time. (Verification requires that the units 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 arecompleted.
