VTrak E-Class Product Manual - Promise Technology, Inc.

VTrak E-Class Product Manual
Logical Drive Settings
After you have created a logical drive, you can click on the Settings tab and
manually change the Preferred Controller ID between Controller 1 and Controller
2. See “Making Logical Drive Settings” on page 136.
If you create logical drives with LUN Affinity disabled, the Preferred Controller ID
will show N/A, and your logical drives will be visible to both controllers.
If you create logical drives with LUN Affinity disabled, and later you enable LUN
Affinity, all of your logical drives will be assigned to Controller 1. To balance the
load, you can reassign some of your logical drives to Controller 2 under the
Preferred Controller ID in the Settings tab. See “Making Logical Drive Settings”
on page 136.
When you a delete a logical drive, the remaining logical drives keep the same
Controller assignments. If you want to rebalance controller assignments of the
remaining logical drives, change their Preferred Controller IDs in the Settings tab.
Failover and Failback
When one controller fails, the surviving controller takes over logical drive access
until the failed controller is brought back online or is replaced. For example, LUN
Affinity is enabled and your logical drives are assigned to Controller 1. The
following actions will happen:
• If Controller 1 goes offline, Controller 2 takes over access to the logical
drives assigned to Controller 1.
• If Controller 1 comes back online, Controller 1 takes back access to the
logical drives assigned to it.
• If Controller 1 is replaced, the new controller takes over access to the logical
drives assigned to Controller 1.
• All logical drives assigned to Controller 2 remain accessible by Controller 2.
Controller 1 cannot access them at any time.
Capacity Coercion
This feature is designed for fault-tolerant logical drives (RAID 1, 1E, 5, 10, 50,
and 60). It is generally recommended to use physical drives of the same size in
your disk arrays. When this is not possible, physical drives of different sizes will
work but the system must adjust for the size differences by reducing or coercing
the capacity of the larger drives to match the smaller ones. With VTrak, you can
choose to enable Capacity Coercion and any one of four methods.
Enable Capacity Coercion and select the Method in the Controller Settings menu.
See page 107. The choices are:
250