IBM SG24-4576-00 Setting the Write Policy, Initializing the Array, Select Change write policy

3.5.6 Setting the Write Policy

Now that the logical drives have been created, you may wish to change the write policy for these drives.

If you want to change the write policy:

1.Select Advanced functions from the main menu.

2.Select Change write policy.

3.Use the up and down arrow keys to select the logical drive.

4.Press Enter to toggle the write policy.

The different options are:

WB for Write-Back:In the write-back mode, the completion status is sent before the data is actually written to the drives. While this mode will yield higher performance, it is critical to protect the DASD power to ensure the write operations actually complete, since the processor thinks the operation has been completed.

WT for Write-Through:In write-through mode, the data is written directly to disk and no acknowledgement is sent until the operation is complete.

3.5.7 Initializing the Array

If you are using RAID Level 1 or 5, you must select Initialize logical drives for proper operation. This sets the drive to a predetermined state. Any data existing on the drive is overwritten with zeros, and the corresponding parity is initialized to the correct value.

1.Select Initialize/synchronize array from the main menu.

2.Select Initialize logical drive.

3.Select the logical drive you want to initialize by pressing the spacebar.

4.Press Enter to start the initialization.

5.Select Yes to confirm.

3.5.8Backup/Restoring the Configuration

Attention!

The array configuration is stored on EEPROM on the adapter. It is very important to back up this configuration on a diskette. If the adapter ever needs to be replaced, the configuration can be restored to the new adapter without the need to reconfigure the array. Otherwise, the array would need to be redefined and your data would be lost.

This is important not only at installation time but whenever the array configuration changes. For example, if a hot-spare drive is defined and subsequently, a drive fails and the hot-spare is enabled, the array configuration is updated. If you are unable to restore the configuration exactly as it was before, it would have the same effect as re-initializing the arrays: all data would be lost.

We strongly recommend that the configuration be backed up.

To back up the configuration:

1. Select Advanced functions from the Main Menu.

112NetWare Integration Guide