Configuration Options When Creating a Unit

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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.
When you configure a new unit, you specify the following:

| Drives to be included in the unit

| Name of the unit (optional)

| Type of configuration (RAID Level)

| Stripe size, if appropriate for the RAID level

| Unit policies that affect how the unit will be handled

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 by Migrating and Setting Unit Policies.

| Note: If you will install the operating system on and boot from a unit managed through the new 3ware RAID controller, see Chapter 3, “First-Time RAID COnfiguration” in the 3ware SATA+SAS RAID Controller Card Software Users Guide, Version 10.02.

Drives to be included in the unit
You may include from one to thirty-two 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 Determining Which RAID Level to Use.)
When creating units on the 9750 controller, you cannot mix SAS and SATA drives in the same unit.
Available drives are those that are not currently part of a unit. If you want to use drives that are currently part of a different unit, you must first delete that unit 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 a unit, see Adding a Drive.
Name of the unit (optional)
Units can be given names for easier identification. These names will be visible in 3DM2, CLI, and 3BM.
Type of configuration (RAID Level)
Available configuration types include RAID 0, RAID 1, RAID 5, RAID 6, RAID 10, RAID 50, and Single Disk. For information about the different RAID levels, see Understanding RAID Concepts and Levels

| Warning: Creating a unit writes the DCB and makes any earlier data on the drives inaccessible.

Stripe size, if appropriate for the RAID level
Striping is not applicable for RAID 1 units or single drives.It used only for RAID 0, RAID 10, RAID 5, RAID 50, and RAID 6 units.
Striping is not applicable for RAID 1, because it is a mirrored array without striping.
Using the default stripe size of 256 KB 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.
Boot volume size
When you create a unit through 3BM or CLI, you can create a special volume to function as the boot volume. This is useful if you are 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 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 can only be specified in 3BM and CLI.
Unit policies
Several unit policies are set when you create a new unit:

| Write Cache (enabled, by default)

| Read Cache (Intelligent, by default)

| Drive Queuing (enabled, by default)

| Ignore ECC (Continue on Source Error When Rebuilding (disabled, by default))

| StorSave Profile (Balanced, by default)

| Auto-Verify (enabled, by default)

| Rapid RAID Recovery (enabled, by default)

The particular policies that you can adjust when you create the unit vary, depending on which program you are using: 3DM2, 3BM, or the CLI.
You can change all of these policies after the unit has been created, with one exception. If Rapid RAID Recovery is disabled, it cannot be enabled later.
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.

Related Topics
  Creating a Unit
  Naming a Unit
  Enabling and Disabling the Unit Write Cache
  Enabling or Disabling Auto-Verify for a Unit
  Setting Overwrite ECC (Continue on Source Error When Rebuilding)
  Enabling and Disabling Queuing for a Unit
  Setting the StorSave Profile for a Unit
  Changing An Existing Configuration by Migrating

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