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Galaxy 65 User Guide
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7.10 Array Problems
Problem: Array is much smaller than it should be.
The backoff percent may be set higher than 1%, which is causing the array to be much smaller than the
full size of its member disks.
Note
We strongly recommend that you leave the backoff percent at 1%.
Setting the backoff percent “backs off” or reduces the capacity of the array by the given percentage. The
backoff percentage helps when you assign spares by compensating for the minor capacity differences
that occur between vendors. For example, two 18-GB drives from two different vendors may differ in
capacity by 100 MB. With a backoff of 0%, you would not be able to replace an array member’s slightly
larger 18-GB drive with a smaller 18-GB drive. If you intend to only use identical drives from the same
vendor, you can use a backoff of 0%.
The default setting is 1% backoff. This default allows you to easily work with drives that have the same
nominal capacity, but different actual capacities. The backoff percentage affects all arrays created on the
Galaxy 65 Subsystem after you set the percentage.
If the drives in an array are not equal in size, the array capacity in a RAID 5 array is based on the smallest
member’s capacity. The backoff percentage is then taken off the capacity from that amount.
7.10.1 Changing the Backoff Percent Using SAM
To change the backoff percentage:
1 From SAM, select Manage Galaxy 65 Subsystem > General Config > Option Configuration.
The Option Configuration page displays.
2 Enter the Backoff Percent you want.
Enter the percentage as three digits using the following format: 00.0%. The default is 01.0%.
7.10.2 Changing the Backoff Percent Using the Disk Array
Administrator
A change to this setting on either SM module is automatically updated on the other SM module.
To change the backoff percentage:
1 From the System Menu, select Configuration Menu and press Enter.
The Configuration Menu displays.
2
Select
Backoff Percent
and press
Enter
.
The Backoff Percent screen displays.
3
Enter the Backoff Percent you want to use and press
Enter
.
Enter the percentage as three digits using the following format: 00.0%. The default is 01.0%.