Viewing and Seting Controller Policies
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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 1TB. (
Note: If a specific Boot Volume was also specified in 3BM,
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” on page 130.)
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
1TB 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.
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