Configuration Options When Creating a Unit

This section provides an overview of the choices you have when configuring a new unit. For step-by-step instructions, see Creating a Unit.

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 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.

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 RAID 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)

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 a smaller or larger stripe size.

Unit policies

Write Cache (enabled, by default)

Drive Queuing (disabled, by default). Available only for 9550SX and 9590SE controllers.

Auto-Verify (disabled, by default)

Continue on Source Error When Rebuild (disabled, by default).

StorSave Profile (Protection, by default) Available only for 9550SX and 9590SE controllers.

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.

In 3DM and using the CLI, you can enable/disable write cache, enable Auto-Verify, and specify whether to continue on source error

In 3BM, you can specify all policies except Auto-Verify

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

Boot volume size

When you create a unit through 3BM, you can create a special volume to function as the boot volume. You specify the size you want this volume to be. This is useful if you will be installing an operating system onto the unit, and want it to be installed in one volume and have a separate volume for data.

This is an optional feature. You do not have to create a boot volume if you plan to install the operating system on the unit.

If you are creating a very large unit (2 TB or greater) and have enabled the Auto-Carving policy, the boot volume will be created in addition to any volumes created through auto-carving. For more information about auto-carving, see Using Auto-Carving for Multi LUN Support.

This feature is only available on 9550SX and 9590SE controllers, and can only be specified in 3BM.