Configuring the Disk Array

The information contained in this section applies only to disk array models.  This section provides step-by-step procedures to perform the tasks necessary to configure, add, change, or delete one or more disk arrays.

Subtopics:
Before You Begin
        RAID Technology
        Hard Disk Drive Capacities
        Additional Storage Capacity
        The RAID Configuration Program Screens
Starting the RAID Configuration Program
Viewing the RAID Configuration
Performing Common Tasks
        Defining a Hot-Spare Drive
        Deleting a Disk Array
        Creating a Disk Array
        Adding Drives to Create an Additional Array
        Defining Logical Drives
Drive Maintenance
        Obtaining Drive Status
           Bay/Array Selection List   (List of all Drive Status Codes)
           Blank Status
        Results of a Hard Disk Drive Failure
        Logical and Hard Disk Drive Status Indications
        Replacing a Faulty Drive
        Redefining Space in an Array
Advanced Functions
        Backing Up Your Disk-Array Configuration
        Restoring the Disk-Array Configuration
        Using the Advanced Functions
           Changing the Write Policy
           Formatting Drives
           Changing the RAID Parameters
Administration Monitoring Utilities
o Drivers
 

Before You Begin
o If you did not create an IBM RAID controller diskette,
o Familiarize yourself with the information contained in this section and the RAID information in the User's Reference.
o Verify the disk-array configuration.  Your disk-array model comes configured as one logical drive.
   - To view disk-array configuration, go to Viewing the RAID Configuration and select View Configuration from the Main Menu.
   - To create a disk array, go to Creating a Disk Array.
o Backup the disk-array configuration.  See Backing Up Your Disk-Array Configuration.
   After you configure the disk array, you can complete setup by installing your operating system (from the diskettes that came with your operating system).

Subtopics:
o RAID Technology
o Hard Disk Drive Capacities
o Additional Storage Capacity
o The RAID Configuration Program Screens

RAID Technology
RAID is the technology of grouping several hard disk drives in a server into an array that can be defined as a single logical drive.  This logical drive then appears to the operating system as a single physical drive.  This grouping technique greatly enhances logical-drive capacity and performance.  In addition, if one of the hard-disk drives fails (becomes defunct) the system continues to run, with no operator intervention required, at reduced performance.  The defunct drive can be replaced without turning off the server (hot-swap).  For more information about hot-swappable hard disk drives, see Installing Internal Drives.

Hard Disk Drive Capacities
With a server, it is important to understand the implications of hard disk drive capacities and how they influence the way you create disk arrays.
   Drives in the disk array can be of different capacities.  For example, if your model came with two 1GB hard disk drives and you install a 2GB hard disk drive to create a RAID 5 disk array, the total capacity of the array is 3GB instead of 4GB.  Therefore, when creating arrays it is wise to add drives of equal capacity.

Additional Storage Capacity
When you add hard disk drives to your server, you must configure a new disk array before you can use the drives.  You can either reconfigure the existing disk array to include the capacity offered with the added drives, or group the added drives into their own array (see Adding Drives to Create an Additional Array).  You also can create an array with only one drive.

The RAID Configuration Program Screens
When you configure your disk array, or even just view its configuration, you will be using the IBM RAID configuration program on the IBM SCSI-2 Fast/Wide Streaming-RAID Adapter/A Option Diskette (also called the IBM RAID controller diskette).  The following figure is a compilation of many of the IBM RAID Controller Disk Array Configuration (also called the IBM RAID configuration program) screens.  The list below the figure gives explanations of the numbered areas of the figure.
 
 

1.  This pop-up allows you to select the RAID level you want to assign to the logical drive you are defining, and it allows you to select the logical drive size.  You can enter the size, in megabytes, or you can accept the default value shown.
    When you need to confirm an action, the Confirm pop-up appears in this area.
 2. You can select any of the choices that appear on the menus.
 3. The Bay/Array selection list shows each bay in the server (for each channel) numbered 1 through 7.  The abbreviation in the bay indicates the status of the drive installed in the bay.  Selections are made from this list to determine which bays (hard disk drives) are in your arrays.  The letter to the right of the bay, identifies the array in which the hard disk drive in that bay is grouped.
    Note:  The Channel/Bay/Array area on the screen does not reflect the physical configuration of the server.  In your server, the hard disk drives are installed in horizontal banks of bays (in banks C, D, and E there are 6 bays, numbered 1 through 6 from left to right).  See Installing Internal Drives to see the physical location of the hard disk drives.
 4. The Array list shows you the array ID and the size (in megabytes) of the array.
    Note:  The capacity (size) is shown in binary equivalent. When a drive is being rebuilt, this area, along with the Logical Drive list area, shows the progression of the rebuilding process.
 5. The Logical Drive list identifies the logical drive (for example, A1), the size of the logical drive, the RAID level assigned to the logical drive, the date it was created, and the write policy.
    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 drive or do a rebuild operation.  (You will have received a message telling you the drive is in a Critical state.)  Offline means that the logical drive is nonrecoverable; the data in that drive is lost.
    When a drive is being rebuilt, this area, along with the Array list area, shows the progression of the rebuilding process.
    Note:  The capacity (size) is shown in binary equivalent. During an initialization process, the Write Policy area displays the percent initialized; during a synchronization process, it displays the percent synchronized.
 6. The information area tells you the action you can perform on this screen or pop-up.

Starting the RAID Configuration Program
You can run the IBM RAID configuration program from diskette or from the ServerGuide CD.  It will be invoked automatically from the ServerGuide CD if the disk array has never been partitioned and if there is no user data present.  However, updated configuration information must be written to diskette.  If you have not yet created the IBM SCSI-2 Fast/Wide Streaming-RAID Adapter/A Option Diskette (RAID controller diskette), go to Starting the Server.

To start the RAID configuration program, insert the IBM RAID controller diskette into the primary drive and turn on the system.  If the system already is on, press Ctrl+Alt+Del.

If you have more than one RAID adapter, you will get an adapter selection screen.  Otherwise, the Main Menu appears.
   You can select Help from any menu.  To return to the previous screen or to the previous work area of a screen, press Esc.  To select a menu item, press the number of the item or use the Up Arrow or Down Arrow to highlight the item, then press Enter.

The Main Menu contains the following choices:
o Help:  Select this choice when you need additional information.
o View configuration: Select this choice to see the existing disk array configuration.
o Create/delete array:  Select this choice to define a hot-spare drive, select the drives for an array you want to create, or to delete an existing array.  This choice also has choices for defining a logical drive and formatting a drive.
  Whenever you make changes to the disk-array configuration and select Exit, the Confirm pop-up window will appear.  You must select Yes to save and activate the changes.
o Initialize/synchronize array:  Select this choice after creating an array to:
   - Set the drive to a predetermined value.  For proper operation of RAID levels 1 or 5, you must select Initialize/synchronize array.  Any data existing on the drive is overwritten with zeros, and the corresponding parity information is initialized to the correct value. You can choose to initialize more than one logical drive at a time.  Also, you can interrupt the initialization process at any time by pressing Esc.  Then, you can either restart the initialization process by pressing Enter, or you can end the process by pressing Esc again.
   - Synchronize logical drive: This selection recomputes and rewrites the parity data on the drive.  You can select this choice to recompute parity data for RAID levels 1 or 5.  This selection does not alter data on the drive.  The synchronization process can be done on multiple logical drives.
o Rebuild device:  Select this to rebuild logical drives.  The rebuild operation is supported only for RAID levels 1 and 5.
o Advanced functions:  Select this choice to change the write policy (the way data is written to the drive), to save your configuration information to a diskette, to restore it from a diskette, or to change RAID parameters.  This choice also allows you to do a low-level format.
o Drive information:  Select this choice to view information about the SCSI devices (hard disk, CD-ROM, tape, and so on) connected to the RAID adapter.
o Exit:  Select this choice to leave the Main Menu.

Viewing the RAID Configuration
Before creating or changing a disk array, you can look at the current configuration by selecting View Configuration from the Main Menu of the RAID configuration program.

To view the disk-array configuration:
 1. Start the RAID configuration program by inserting the IBM RAID controller diskette into the primary drive and turning on the system.  If the system already is on, press Ctrl+Alt+Del.
 2. Select View configuration.  The current disk-array configuration information appears on the screen.
 3. Press Enter to see the stripe order in the Bays Occupied (Ch:Bay) field.
 4. Press any key to continue.
 5. Press Esc to return to the Main Menu.

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