User's Manual

Configuring an Array
5-10 HP Smart Array 641/642 Controller User Guide
HP CONFIDENTIAL
Writer: John Turner File Name: f-ch5 configuring an array
Codename: darkmatter - antimatter Part Number: 309311-001 Last Saved On: 11/6/02 4:17 PM
Configuring the New Logical Drive
1. In the Logical Configuration View panel, highlight the new logical drive that
you want to configure, and then press the Enter key.
2. Select Fault Tolerance in the Logical Drive Options menu, and then press the
Enter key.
3. Choose the RAID level that you want and then press the Enter key.
4. Choose Stripe Size and then press the Enter key.
5. Choose the stripe size that you want and then press the Enter key.
6. Press the Esc key to accept the settings and return to the main manual
configuration screen.
Configuring the Controller Settings
The Controller Settings option allows you to choose the drive rebuild priority,
expansion priority, and accelerator ratio for all arrays on the controller.
• With a low priority setting, a rebuild or expansion takes place only when the
array controller is not busy handling normal I/O requests. This setting has
minimal effect on normal I/O operations. However, there is an increased risk that
data will be lost if another physical drive fails while the rebuild is in progress.
• With a high priority setting, the rebuild or expansion occurs at the expense of
normal I/O operations. Although performance is affected, this setting provides
better data protection because the array is vulnerable to additional drive failures
for a shorter time.
• At the medium priority setting, expansion or rebuild occurs for half of the time,
and normal I/O requests are handled during the rest of the time.
NOTE: Logical drives can be rebuilt only if they have been configured for fault tolerance (that
is, any RAID level other than RAID 0). Drive rebuild begins automatically after you have
replaced a failed physical drive in the array.
The accelerator read/write ratio determines the amount of memory allocated to the
read and write caches on the array accelerator. Different applications have different
optimum settings. Some controllers (especially those without battery-backed write
cache) do not allow this ratio to be changed.