User guide

Chapter 11. 3DM 2 Reference
196 3ware Serial ATA RAID Controller User Guide
The five radio buttons let you set the ratio at which background tasks are
performed in comparison to I/O. For additional information, see “Setting
Background Task Rate” on page 155.
Unit Policies
You can enable or disable these policies: Write Cache, Auto-verify,
Continue on Source Error During Rebuild, Queuing, and you can select a
StorSave Profile. 3DM lists each unit on the current controller, and shows
you whether the policies are currently enabled or disabled for each unit.
Write Cache. When write cache is enabled, data is stored locally in memory
on the drive before it is written to the disk drive media, allowing the computer
to continue with its next task. This improves performance. However, in the
event of a power failure, the data in the write cache will be lost if you do not
have a battery backup unit (BBU) or an uninterruptable power supply (UPS).
For additional information, see “Enabling and Disabling the Unit Write
Cache” on page 108.
Auto Verify. When the Auto Verify policy is enabled, a verify task is
performed automatically once every 24 hours. This feature is designed to
make regular verification of units easier.
If a verify scheduling window has been set up and enabled, then Auto Verify
will wait until the scheduled time window to start the automatic verify
process.
When Auto Verify is not enabled, verify tasks are only run if you manually
request one on the 3DM
Management page. If a verify scheduling window is
set and enabled, then manual verifies will wait until the scheduled time to
start.
Continue on Source Error During Rebuild. This policy applies only to units
which are redundant. (For units which are not redundant, a check box is not
available.) When this policy is set, ECC errors are ignored when they are
encountered during a rebuild. When this policy is not set, a rebuild will abort
upon encountering an ECC error and the unit will be set back to Degraded.
Since this option could result in the loss of some source data in the event of
source errors, select this option only if you want to ensure that a rebuild will
complete successfully without manual intervention. If the rebuild fails and
Continue on Source Error During Rebuild is not selected, then you have the
option to start a rebuild manually. It is recommended that you execute a file
system check when the rebuild completes. Under Windows, you can do this
by right-clicking on the Drive and choosing Properties; then on the Tools tab,
click Check Now. Under Linux or FreeBSD use
fsck /dev/sda1.