3DM 2 Online Help

Using Auto-Carving for Multi LUN Support
When the Auto-Carving policy is on, any unit larger than a specified size (known as the carve size) is 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 2TB 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.
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 2 TB (1024 MB to 2048 MB). 3ware firmware supports a maximum of 8 volumes per controller, up to a total of 16 TB.
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: Using auto-carving can have an impact on performance.

The main use of auto-carving is to gain use of the full capacity in units greater than 2 TB. This is because Windows 2000, Windows 2003, Windows XP, and FreeBSD 4.x, do not currently recognize unit capacity in excess of 2 TB.

| Note: Operating systems without this limitation include Linux 2.6, FreeBSD 5.x, Windows XP-64bit, and Windows 2003, SP 1. 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 3DM, enable Auto-Carving at the bottom of the Management > Controller Settings page.

2 | Show 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 3DM 2, 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 is always 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
  Exporting JBOD Disks

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