You create LVM2 regions from the freespace in LVM2 containers. If there is at least one extent of freespace in the container, you can create a new region.
The following options are available for creating LVM2 regions:
The name of the new region.
The size of the new region. This size must be a multiple of the container's extent-size. If it isn't, the size will be rounded down as appropriate. By default, all of the available freespace in the container will be used for the new region.
If the container consumes two or more objects, and each object has unallocated extents, then the new region can be striped across multiple objects. This is similar to RAID-0 striping and achieves an increased amount of I/O throughput. This option specifies how many objects the new region should be striped across. By default, new regions are not striped, and this value is set to 1.
The granularity of striping. The default value is 64 KB. Use this option only if the stripes option is greater than 1.
A list of names of the objects the new region should map to. By default, this list is empty, which means all available objects will be used to allocate space to the new region.
You can expand an existing LVM region if there are any unused extents in the container. The following options are available for expanding LVM regions.
The amount of space to add to the region. This is a delta-size, not the new absolute size of the region. As with creating new regions, this size must be a multiple of the container's extent-size, and will be rounded down if necessary.
The number of objects to stripe this new portion of the region across. This value can be different than the number of stripes in the existing region. For example, if the region was created originally with three stripes, but now only two objects are available, then the new portion of the region could be striped across just those two objects. The number of stripes for the last mapping in the region will be used as the default.
The granularity of striping. As with the number of stripes, this value can be different than the stripe-size for the existing region. By default, the stripe-size of the last mapping in the region is used.
A list of names of the objects the region should be expanded onto. By default, this list is empty, which means all available objects will be used to allocate additional space for the region.
You can shrink an existing LVM region by removing extents from the end of the region. Regions must have at least one extent, so regions cannot be shrunk to zero.
The following options are available when shrinking LVM regions. Because regions are always shrunk by removing space from the end of the region, a list of objects cannot be specified in this command.
The amount of space to remove from the region. This is a delta-size, not the new absolute size of the region. As with creating and expanding regions, this size must be a multiple of the container's extent-size, and will be rounded down if necessary.
You can delete an existing LVM region as long as it is not currently a compatibility volume, an EVMS volume, or consumed by another EVMS plug-in. No options are available for deleting LVM regions.
You can rename an existing LVM2 region. In the EVMS GUI and text-mode UIs, this is done using the modify properties command, which is available through the "Actions" menu or the context-sensitive pop-up menus. In the EVMS CLI, this is done using the set command.
If the renamed LVM2 region has a compatibility volume on it, then the name of that compatibility volume will also change. In order for this to work correctly, that volume must be unmounted before the name is changed. Also, be sure to update your /etc/fstab file if the volume is listed, or the volume won't be mounted properly the next time the system boots.
If the renamed LVM2 region has an EVMS volume or another storage object built on it, then the region's name change will be transparent to the upper layers. In this case, the rename can be done while the volume is mounted.