HP Compaq Integrated Smart Array Controller - Manual (Page 86)

6-18 Compaq Integrated Smart Array Controller User Guide
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Part Number: 153236-001 File Name: g-ch6 Compaq Array Configuration Utility.doc Last Saved On: 8/27/99 11:25 AM
Priority Settings
To set the drive rebuild priority, highlight the Integrated Smart Array
Controller in Controller Options frame and select Controller Settings. If you
choose low priority for a drive rebuild, drive rebuilding takes place when the
drive is idle. If you choose high priority, drive rebuilding takes place while the
drive is active, at the expense of normal I/O operations. Choosing high priority
for drive rebuilding protects the array, but the array is vulnerable to additional
drive failures while a drive is both in operation and being rebuilt.
Accelerator Ratio
The Integrated Smart Array Controller onboard cache only performs
read-ahead caching. Therefore, the ratio is always 100% read to 0% write.
This read cache option can be disabled in the Array Accelerator frame on the
Create Logical Drive screen.
Expand an Array
Overall server performance may be slightly degraded during an array
expansion procedure. In most cases, degradation can be offset with additional
physical drives.
■ To further minimize performance degradation, perform the capacity
expansion process during periods of low server use. If you must expand
during peak periods, the Array Configuration Utility for NetWare allows
you to set the priority of the expansion. Setting a low priority affects
performance the least, but it takes longer for the new space to become
available.
■ For expansion purposes, avoid using drives that have a greater capacity
than the smallest drive in the array. Adding larger drives wastes space
because only the space that is equal to the smallest drive size can be
used.
Add or Configure Spare Drives
When adding a spare drive to an array, you must have an unassigned drive or a
drive already assigned as a spare on another array. You can assign a single
spare to as many arrays as you want, or assign separate spares. When you
select Assign Spare Drive, only drives that qualify will appear. For example,
only those spares that are large enough will appear. If drives that you expect to
see do not appear, switch to the physical drive view and check the size of the
drives. The spare must be as large as the smallest drive in the array.