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PC Server 500 - Defining logical drives
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Defining Logical Drives
After you have created an array, you must define a logical drive. (You cannot leave the RAID configuration program until you define the logical drives for any created arrays.)

To define a logical drive:
1. Select Define Logical drive from the Create/Delete Array menu. The Create/Delete Array menu screen appears; the cursor is active in the Array list.
2. Use the Up Arrow (« ) key or the Down Arrow (» ) key to highlight the array you want to define; then press Enter. The Select RAID Level pop-up window appears, and the cursor is active in the window.

The system automatically assigns RAID level 0 to any logical drives defined in an array containing only one hard disk drive. When this is the case, the Select RAID Level pop-up window will not appear.

If you have only two hard disk drives in the array, the Select RAID Level pop-up window appears, but RAID level 5 is not selectable because you need at least three hard disk drives in an array to assign RAID level 5 to one of the logical drives. You can define more than one logical drive for your array. The only restriction is that the maximum number of logical drives you can define is eight.
3. Use the Up Arrow (« ) key or the Down Arrow (» ) key to highlight the RAID level you want to assign to these logical drives, then press Enter.

Because the level you assign can influence the space needed for the drive, you must assign a RAID level before you enter the size of the logical drive.

The Logical Drive list shows you the logical drive ID, the size of each logical drive, the RAID level you assigned to that logical drive, and the date that the logical drive was created.

The status of the logical drive also is shown. Good means that all is well with the drive. Critical means that you must replace the hard disk drive or do a rebuild operation. (You will have received a message telling you what has happened to the drive.) Offline means that the logical drive is unrecoverable; the data on that drive is lost.

The Logical Drive Size pop-up window shows the space in this array that is available for logical drives.

4. Type the size, in megabytes, that you want for the logical drive; then press Enter. A pop-up window appears asking you to confirm your action.

Information about the new logical drive appears in the Logical Drive list.

The size appearing in the Logical Drive list might be different from the size you typed because it appears in binary equivalent.

The size of a logical drive is determined by a number of factors, but basically the size must be divisible by the number of drives in the array.

Consider the following examples:
Example 1:
There are three 1GB drives in the array. You assign RAID level 0 (which uses all the drives in the array with no parity storage), and type '1000MB.´ The 'Size (MB)´ will be 999, which is the number closest to and lower than 1000 that is divisible by 3.

Example 2:
There are three 1GB drives in the array, and you assign RAID level 5. Data is striped across all three drives in the array, but the space equivalent to that of one drive is used for redundant storage. Therefore, if you type '1000MB,´ the 'Size (MB)´ remains 1000 because it is divisible by 2 (drives), which is the space available for data.

If you do not use the entire array for this logical drive, you can create another by assigning either the same or a different RAID level for an additional logical drive. You can have as many as eight logical drives among four disk arrays.

5. To return to the Create/Delete Array menu, press Esc. To define more logical drives, repeat steps 1 through 5 of this procedure.

6. To leave this screen, select Exit or press Esc. A pop-up window appears asking you to confirm your action.

7. To save your changes, select Yes. To maintain the disk-array configuration that was in place before you made changes, select No.

8. If you are using RAID level 1 or RAID level 5, you must select Initialize logical drive for proper operation. This sets the drive to a predetermined state. Any data existing on the drive is overwritten with zeros, and corresponding parity is initialized to the correct value
a. Select Initialize/synchronize array from the Main Menu; then select Initialize logical drive.
b. Select the logical drives you want to initialize from the Logical Drive list by pressing the Spacebar (the selected drives will appear highlighted). To start the initialization, press Enter. A pop-up window appears asking you to confirm your action.

If you select Yes in the Confirm pop-up window, information in the logical drive will be overwritten with zeros.

c. Select Yes to confirm that you want to initialize this logical drive.
The initialization process begins, and you can see its progress in the Pct. Int. (Percent Initialized) column of the Logical Drive list.
d. To stop the initialization at any time, press Esc. Then press Esc again to return to the menu, or press Enter to continue initializing the drive.

9. To back up the disk-array configuration to diskette, you will need a 3.5-inch formatted diskette. To back up the disk-array configuration:
a. Select Advanced functions from the Main Menu.
b. Select Backup config. to diskette.

Follow the instructions on the screen. A pop-up window shows the default file name of CONFIG. You can change the file name by typing over the default. The Backup program will assign a file-name extension of .dmc.
Document id:  DDSE-3UVTYF
Last modified:  1999-01-25
Copyright 2002 IBM Corporation
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