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Creating a New Unit

When you create a new unit, you specify the following:

You can make some types of changes to the RAID configuration later, and you can change the unit name and the unit policies. For details, see Changing An Existing Configuration.

Note: If you will install the operating system on and boot from a unit managed through the new 3ware RAID controller, you should configure the unit using 3BM 2. For details, see Chapter 3, "First-Time RAID Configuration using 3BM," in 3ware 9550SX Serial ATA RAID Controller User Guide.

Drives to be included in the unit

You may include from one to sixteen drives in the unit, depending on the number of drives available and the model of the controller you have. (For information about how many drives to select for a given RAID level, see Possible Configurations Based on # of Drives.)

You may only select available drives that are not currently part of a unit. If you want to use drives that are currently part of a different unit, you must delete that unit, first, to make the drives available. (For details, see Deleting a Unit.) If drives are listed under "Incomplete Drives and Others," they must be deleted before they can be used.

If you want to add drives to be used in the unit, see Adding a Drive through 3DM.

Type of configuration

Available configuration types include RAID 0, RAID 1, RAID 5, RAID 10, RAID 50, and Single Disk. For information about the different RAID levels, see Understanding RAID Concepts and Levels.

Note: Creating a unit erases all data on all drives. Although creating a RA1D 1 (mirror) creates a unit that will have a duplicate of data on both drives after it is put in use, creating a RAID 1 cannot be used to make a backup copy of data that currently exists on a single drive unless you migrate from a RAID 1 to two individual single disks.

Name of the unit (optional)

Units can be given names. These names will be visible in 3DM and CLI.

Stripe size, if appropriate for the RAID level

In general, smaller stripe sizes are better for sequential I/O, such as video, and larger stripe sizes are better for random I/O (such as databases).

Striping size is not applicable for RAID 1, because it is a mirrored array without striping.

Using the default stripe size of 64KB usually gives you the best performance for mixed I/Os. If your application has some specific I/O pattern (purely sequential or purely random), you might want to experiment with smaller or larger stripe size.

Unit policies

Several unit policies are set when you create a new unit:

The particular policies that you can adjust when you create the unit vary, depending on which program you are using: 3DM, 3BM, or the CLI.

You can change all of these policies after the unit has been created.

For a summary of what these policies do, see the discussion under Unit Policies in the section Controller Settings Page. For how to adjust each one, see the procedures later in this chapter.

To create a unit

  1. In 3DM, choose Management > Maintenance.
  2. In the Available Drives list, select the drives you want to include in the unit by marking the checkbox in front of the Port number for each one.
  3. If you are creating single drive units (single disks or hot spares), you can configure multiple drives at once.

    (For details about this screen, see Maintenance Page.)

  4. Click Create Unit.
  5. A window like the one shown here shows the drives you selected, and lets you specify configuration settings.

  6. In the window, select the RAID configuration you want.
  7. If stripe size applies to the RAID type you select, select a Stripe Size.
  8. Optional: In the Name box, enter a name for the unit (up to 21 characters, including dashes and underscores).
  9. If you have 12 drives attached to the controller and selected RAID 50 as the configuration in step 3, select whether you want 3, 4, or 6 Drives Per Subunit, as shown here.
  10. Make changes to the unit policies, as desired. You can enable or disable the Write Cache, Auto-Verify, and Continue on Source Error During Rebuild. You can also set the StorSave policy.
  11. Click Ok.
  12. The new unit will appear in the Unit Maintenance list at the top of the page and the operating system will be notified of the new unit.

    In Linux, a device node will now be associated with each unit created. In Windows, the device manager will reflect the changes under the disk drives icon.

  13. Partition and format the unit. Steps will vary depending on the operating system. For more information, see Partitioning and Formatting Units.
  14. Mount the new unit.
  15. Note: For RAID 5 units with 5 or more disks, and RAID 50 units with subunits of 6 drives, initialization of the unit begins immediately.
    The unit can be used while it is initializing and is fault-tolerant.

  16. Partition and format the unit. For details, see Partitioning and Formatting Units.

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