Cybernetics miSAN-V6, Руководство оператора

Страница: 125 / 190

125 Using the 3ware Disk Manager®
Cybernetics UM-MV-86-B1-0801
Background Task Rate
The Background Task Rate fields let you change the balance of background tasks and I/
O performed by the controller.
The 5 radio buttons let you set the ratio at which background tasks are performed in com-
parison to I/O. The furthest left buttons set the firmware to the fastest settings for back-
ground tasks settings. This means, maximum processing time will be given to
background tasks rather than I/O. The furthest right buttons set the firmware to the slow-
est background rates, giving maximum processing time to I/O.
Unit Policies
You can enable or disable two policies: Auto-verify and Continue on Source Error During
Rebuild. 3DM lists each unit on the controller specified in the drop-down list on the menu
bar, and shows you whether the policies are currently enabled or disabled for each unit.
• Write Cache : You can enable or disable write cache for each unit. 3DM lists each unit
on the controller specified in the drop-down list on the menu bar, and shows you
whether the write cache is currently enabled or disabled for it. Write cache is a
combination of the physical hard drives’ write cache as well as the controller’s
memory, depending on what type of unit you are using.
• Auto-verify : The Auto-verify policy causes verify tasks to be performed automatically,
whenever the controller firmware algorithms determine that a verify task is needed.
This feature is designed to make verification of units easier. When you check this box,
the controller will run verify tasks as they are required.
If there is no schedule set up for verify tasks, then the controller firmware can initiate
a verify task at any time. If a verify time window is scheduled, then the controller will
not start a verify task for that unit outside the time window, and may or may not start a
verify task for that unit within the time window, depending on whether one is needed.
If Auto-verify is not set and there is no schedule, you must manually specify when you
want to run a verify, on the 3DM Management page.
• 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 manually intervention. If the rebuild fails and Continue on
Source Error During Rebuild is not selected, then you have the option to start a rebuild
Caution
Make sure Write Cache is enabled, and do not disable Write Cache for
any units. If Write Cache is disabled, the write/read performance for the
physical hard drives will be noticeably slower.