Chapter 9. Maintaining Units
178 3ware Serial ATA RAID Controller User Guide
occurs. (For more information, see “Setting Background Task Rate” on
page 183.) You can also postpone initialization until a scheduled time. (For
details, see “Scheduling Background Tasks” on page 184).
Note: Units that do not need to be immediately initialized for full
performance will be automatically initialized using background
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 10 on page 179.
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.
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