Avago Technologies 3ware SAS 9750-16i4e - Manual (Page 84)

Chapter 6. Configuring Your Controller
72 3ware SATA+SAS RAID Controller Card Software User Guide, Version 10.2
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” on page 81.)
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.
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.
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.
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 /cx add type
command attribute [v0=n|vol=a:b:c:d ]. See the 3ware SATA+SAS RAID
Controller Card CLI Guide, Version 10.2.
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.