Defining Logical Drives

Defining Logical Drives

You must define at least one logical drive for each array. The ServeRAID controller supports up to eight logical drives. If you have only one array, you can define it as a single logical drive, or you can divide it into several logical drives. If you have two or more arrays, each array can be one logical drive, or you can divide each array into multiple logical drives, as long as the total number of logical drives for all of the arrays does not exceed eight.

Note: Refer to the documentation provided with the operating system for information about the recommended logical drive size.

To define a logical drive:

1.  Select Define Logical Drive from the  Create/Delete/Copy Log Drive menu, then, press Enter
2.  Use the Up Arrow (  ) or Down Arrow (  ) key to  highlight the array for which you want to define a  logical drive, then, press Enter.
    The Select RAID Level pop-up window appears.

   Note:

   1.  Typically, the first logical drive that you define will be the startup (boot) drive.
   2.  The ServeRAID Configuration program 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.
   3.  If you have two hard disk drives in the array, the Select RAID Level pop-up window  appears, but RAID level 5 is not available.  You need at least three hard disk drives in an array to assign RAID level 5 to the logical drives.
   4.  The RAID level that you assign to a logical drive can influence the amount of space that  the drive requires, therefore, you must assign a RAID level before you enter the size of the logical drive.
   5.  For a description of RAID levels 0, 1, and 5,  see 'RAID Classifications'.
   6.  You can define up to eight logical drives for the array. If you plan to use the  logical-drive migration (LDM) procedure, do not define more than seven logical drives.  The LDM procedure requires one free  logical drive. (See 'Logical Drive Migration Administration' for more  information.)
   7.  If you plan to use the Change RAID Level feature of the LDM, you must assign the  same RAID level to all of the logical drives in the array. (See 'Changing RAID Levels' for more information.)

3.  Use the Up Arrow (  ) or Down Arrow (  ) key to highlight the RAID level  that you want to assign to the logical drive, then, press Enter. The Logical Drive  Size pop-up window appears.

    If this is the first logical drive you are defining, the Logical Drive Size pop-up window will show the  amount of free space available in the array.

   Note:  Typically, the first logical drive that you define will be the startup (boot) drive.

    If you already defined other logical drives for this array, the Allocation Table appears showing the  existing logical drive sizes and the amount of free space available.
    The size of a logical drive is determined by several factors, but the size must be divisible by the number  of data drives in the array.  A logical drive in an array can be any size you choose within the size limitations of the array.  Consider the following examples:

   •  Example 1. The array consists of three 1GB drives.  You assign RAID level 0, which uses all the drives in the array with no redundant or  parity storage, then, you type 1000.  The number 999 will appear in the Size (MB) field because it is the number closest to  and lower than 1000 that is divisible by 3.
   •  Example 2. The array consists of three 1GB  drives. You assign RAID level 1, which provides disk mirroring and 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.  If you type 1000, the number 999 will appear in the Size (MB) field.  The physical capacity used is 2000MB, twice that of the logical drive size.  The number that is closest to and lower than 2000 that is divisible by 3 is 1998.  The logical drive size is 999 MB, which is 50% of the physical capacity.
   •  Example 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 1000, the number 1000 remains in the Size (MB)  field because it is divisible by 2 (drives), which is the space available for data.  The physical capacity used is 1500MB.

4.  Type the size, in megabytes, that you want for the logical drive, then, press Enter.
5.  When the Confirm pop-up window appears, select Yes, then, press Enter.

    Information about the new logical drive appears in the Logical Drive list.  If you did not use all of the available free space, you can create another logical drive.  You can assign the same or a different RAID level to additional logical drives.

6.  When a message appears, stating that all logical drives must be initialized, press any key to continue.

   Note:  To ensure that the server operates correctly, you must initialize the new logical drive.  A quick initialization of a logical drive erases the first 1024 sectors on the drive.

7.  When the Confirm pop-up window appears, you have two choices:
   •  Select Yes to perform a quick initialization, then,  press Enter. When the quick initialization is complete, go to step 8.
   •  Select No and if the drive is a RAID level 5  drive, it will be automatically synchronized in the background.  Go to 'Initializing Logical Drives'  to perform a complete initialization.

8.  If you just performed a quick initialization of a RAID level 5 logical drive,  a message appears, stating that the logical drive that you just created is being  synchronized in the background and is ready for data storage.  You have now completed the required steps for creating a ServeRAID configuration.  Continue with the next step in this procedure.
9.  Back up the disk-array configuration information to diskette.  See 'Backing Up the Disk-Array Configuration'  for instructions.

    If you have not already done so, use the information provided in the  ServerGuide package to install the operating system.

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