Defining Logical Drives (ServeRAID)

Defining Logical Drives

After you have created an array, you must define a logical drive. You can use the Administrator and Monitoring program or the ServeRAID configuration program. When you use the Administration and Monitoring program from the active operating system desktop, you do not have to restart the server. Referto the README file on the Administration and Monitoring program for instructions for the operating system. (You cannot leave the ServeRAID configuration program until you define the logical drives for any arrays created.)

To define a logical drive:
  1.  Start the ServeRAID configuration program (see 'Starting the ServeRAID Configuration Program'
  2.  Select Define Logical Drive from the  Create/Delete Array menu. The following screen  appears, the cursor is active in the Bay/Array list.


  3.  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.

    Note:   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 only two hard disk drives are 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 the array. The only restriction is that the maximum  number of logical drives you can define is eight,  the maximum number of physical drives in an array is 8 or 16, depending on the stripe unit size.


    1.  If you are planning to change RAID levels using the Administration and Monitoring program, the  maximum number of logical drives that can be defined is 7. The RAID conversion procedure requires one free logical drive.
    2.  When the stripe unit size is 8K or 16K, the maximum number of drives in an array is 16.  When the stripe unit size is 32K or 64K, the maximum number of drives in an array is 8.

  4.  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.

    Note:   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  contains  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
    OKY means that all is well with the drive.
    CRT means that you must replace the hard disk drive or rebuild the logical drive.
      (You will have received a message during system startup telling you what has happened to the drive.)
    OFL means that the logical drive is irrecoverable, the data on that drive is lost.

     If other logical drives have been defined, the Allocation Table appears, showing the logical drive sizes already created, and the amount  of free space available.

  5.  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.

    Note:   The size appearing in the Logical Drive list might be different  from the size you typed. (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 scenarios:

    Scenario 1: 
     The array consists of three 1GB drives.  You assign RAID level 0 (which  uses all the drives in the array with no parity storage), and type 1000MB . The number in the Size (MB) field  will be 999, which is the number closest to and  lower than 1000 that is divisible by 3.

    Scenario 2: 
     The array consists of three 1GB drives, and you assign RAID level 1.  which provides a disk mirroring that stripes data across all drives in the array.  Because the data is mirrored, the capacity of the logical drive is 50% of the physical capacity  of the hard disk drives grouped in the array.  Therefore, if you  type 1000MB , the number in the Size (MB) field  will be 999. The physical capacity used is 2000MB, twice that of the logical drive size.  The number that is closest to or lower than 2000 and is divisible by 3 is 1998. The logical drive size is  999, wich is 50% of the physical capacity.

    Scenario 3: 
     The array consists of three 1GB drives, 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 number in the Size (MB) field remains 1000 because it is divisable 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 eight disk arrays.

    1.  Select Initialize/Synchronize Log Drive from the Main  Menu, then select Initialize Logical Drive.
    2.  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.

    3.  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.

    4.  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.

    5.  If you defined the drive as RAID level 5, select Initialize/Synchronize Log Drive from  the Main Menu, then, select Synchronize Logical Drive before storing data.

  6.  Note: 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:

    1.  Select Advanced functions from the Main Menu.
    2.  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 .ips .

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