About Verification - 3Ware 9550SXU-12 User Manual

Maintaining Units

About Verification

162
Table 12: Initialization Requirements for Different RAID
Configurations
Initialization Required
for Highest
Performance?
Yes
Background Initialization After Power Failure
The 3ware controller detects and handles power failures, using a mechanism
that ensures that redundant units have consistent data and parity. When a
redundant unit is unexpectedly shutdown, there is a possibility some data and
parity may be inconsistent. If a unit or sub-unit of a redundant unit is detected
to have been shutdown uncleanly, the unit or sub-unit will change its mode to
either 'Initializing' or 'Verifying.'
When the initialization is complete, the unit is guaranteed to be redundant
again. The initialization does not erase user data.
This process will take less time if the unit is created with Rapid RAID
Recovery enabled during unit creation. See "Rapid RAID Recovery" on
page 126.
The verify feature confirms the validity of redundant data on redundant units
and performs media scans on non-redundant units.
Regular weekly verification is a good idea, as it can provide early warning of
a disk drive problem or failure. This allows you to replace drives before they
fail.
You can start a verify manually or regular verification can be done
automatically by enabling Auto Verify. (See "Starting a Verify Manually" on
page 165 and "Using Auto Verification" on page 164.)
During verification, I/O continues normally, but with a slight performance
loss, depending on your verify rate setting. You can adjust how much
verification will slow performance by setting a rate at which it occurs. (See
"Setting Background Task Rate" on page 172.) You can also postpone
verification until a scheduled time. (See "Scheduling Background Tasks" on
page 173.)
3ware SAS/SATA RAID Software User Guide, Version 9.5.1
RAID Configurations
RAID 5 with 5 or more disks
RAID 6
RAID 50 with subunits of 5 or more disks