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Using Auto-Carving for Multi LUN Support
Auto-carving is useful for creating multiple volumes out of large arrays at the hardware level. Then, when you boot to the operating system, each volume appears as a different disk drive, simplifying the partitioning required at the operating system level.
When the Auto-Carving policy is on, any new unit larger than a specified size (known as the carve size) will be created as multiple volumes that can be addressed by the operating system as separate volumes. These chunks are sometimes known as multiple LUNs (logical units). However, throughout the 3ware documentation, they are referred to as volumes.
For example, using the default carve size of 2 TB, if the unit is 2.5 TB then it will contain two volumes, with the first volume containing 2 TB and the second volume containing 0.5 TB. If the unit is 5.0 TB then it will contain 3 volumes, with the first two volumes containing 2 TB each and the last volume containing 1 TB. (Note: If a specific Boot Volume was also specified in 3BM or CLI, the first volume will be the size specified for the Boot Volume, and then the carve size will be applied to the remainder of the unit. For more information, see Boot volume size.)
Each volume can be treated as an individual disk with its own file system. The default carve size is 2 TB; you can change this to a setting in the range of 1 TB to 32 TB (1024 GB to 32768 GB). 3ware firmware supports a maximum of 32 volumes per controller, up to a total of 32 TB.

| Note: CLI provides the ability to specify variable sizes for the first 4 volumes of a unit when auto-carving. This is done while creating a unit with the /c x add type command attribute [v0=n|vol=a:b:c:d]. See the 3ware SATA+SAS RAID Controller Card CLI Guide, Version 10.2.

If you are migrating a unit to a size that is larger than the carve size and auto-carving is on, multiple volumes will be created.

| Note: Carving a unit into multiple volumes can have an impact on performance.

| Note: Even though the Linux 2.6 kernel supports partitions larger than 2 TB, the installers for SUSE and Redhat do not. Turn auto-carving on to prevent the installation from failing.

You must turn on the Auto-Carving policy before creating the unit. Units created with this policy turned off will not be affected by a change to the policy. If the policy is turned off later, units that have been carved into volumes will retain their individual volumes; existing data is not affected.
To use auto-carving

1 | Enable the auto-carving feature.

In 3DM2, enable Auto-Carving at the bottom of the Management >> Controller Settings page.

2 | Create a new unit or migrate an existing unit to include the drives you want to use.

If the combined capacity of the drives exceeds the carve size, a number of volumes will be created.

3 | Verify the creation of the volumes.

In 3DM2, the number of volumes is shown on the Unit Details page.

4 | Verify that the volumes appear in the operating system. They will appear as additional drives.

Notes:

• | If you are configuring a unit for primary storage and it will be greater than 2 TB, be sure to enable the auto-carve policy before creating the unit.

• | When volumes have been created through auto-carving, they cannot be deleted except by deleting the unit.

• | If you create a bootable unit that has multiple volumes, the first volume can be used as the boot device.

• | Changing the auto-carve policy does not affect existing units.

Related Topics
  Viewing Controller Policies
  Setting the Auto-Rebuild Policy
  Setting the Size of Volumes Created with Auto-Carving
  Enabling and Setting Up Staggered Spin-up
  Viewing Information About a Phy
  Changing the Phy Link Speed

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