Adaptec 3200S User Guide - Page 93

Running a Verify Process, Background Task Priority

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Storage Manager Running a Verify Process Running a manual Verify for a RAID array ensures that the redundant information contained in the array is consistent. Note: Data inconsistencies should not occur under normal conditions. However, a power failure that interrupts an array write operation can cause inconsistencies. Making the data consistent again through the Verify function does not ensure that the new consistent data is the correct data. This operation is performed by the RAID controller concurrent with normal system operation and requires no user or host computer intervention. To start data verification on an array, select Verify in the Array Group Information window. If any inconsistencies in the data redundancy are found, they are made consistent. s For RAID 1 arrays, the mirrored drive pairs are compared sector by sector to ensure that both drives contain identical data. s For RAID 5 arrays, parity is recalculated and checked against the stored parity information. s For RAID 0, only a disk media ECC check is performed. Running Verify on an array that is in a degraded state can result in significantly reduced I/O performance. Although there is no impact on the host CPU, system I/O performance can be affected due to increased demand on controller resources. If this is a concern, use the Background Task Priority feature to assign a lower-level priority to background processes. Background Task Priority You can run a rebuild or verification operation without taking an array offline. These operations are performed as background tasks on the RAID controller and are transparent to the host operating system. However, the controller interleaves I/O from the operating system with I/O from the background task and this can affect system performance. 3-48

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3-48
Storage Manager
Running a Verify Process
Running a manual Verify for a RAID array ensures that the
redundant information contained in the array is consistent.
Note:
Data inconsistencies should not occur under normal
conditions. However, a power failure that interrupts an
array write operation can cause inconsistencies. Making the
data consistent again through the Verify function does not
ensure that the new consistent data is the correct data.
This operation is performed by the RAID controller concurrent with
normal system operation and requires no user or host computer
intervention.
To start data verification on an array, select
Verify
in the Array
Group Information window.
If any inconsistencies in the data redundancy are found, they are
made consistent.
■
For RAID 1 arrays, the mirrored drive pairs are compared
sector by sector to ensure that both drives contain identical
data.
■
For RAID 5 arrays, parity is recalculated and checked against
the stored parity information.
■
For RAID 0, only a disk media ECC check is performed.
Running Verify on an array that is in a degraded state can result in
significantly reduced I/O performance. Although there is no impact
on the host CPU, system I/O performance can be affected due to
increased demand on controller resources. If this is a concern, use
the Background Task Priority feature to assign a lower-level priority
to background processes.
Background Task Priority
You can run a rebuild or verification operation without taking an
array offline. These operations are performed as background tasks
on the RAID controller and are transparent to the host operating
system. However, the controller interleaves I/O from the operating
system with I/O from the background task and this can affect
system performance.