16.1. Why expand and shrink volumes?

Expanding and shrinking volumes are common volume operations on most systems. For example, it might be necessary to shrink a particular volume to create free space for another volume to expand into or to create a new volume.

EVMS simplifies the process for expanding and shrinking volumes, and protects the integrity of your data, by coordinating expand and shrink operations with the volume's file system. For example, when shrinking a volume, EVMS first shrinks the underlying file system appropriately to protect the data. When expanding a volume, EVMS expands the file system automatically when new space becomes available.

Not all file system interface modules (FSIM) types supported by EVMS allow shrink and expand operations, and some only perform the operations when the file system is mounted ("online"). The following table details the shrink and expand options available for each type of FSIM.

Table 16-1. FSIM support for expand and shrink operations

FSIM typeShrinksExpands
JFSNoOnline only
XFSNoOnline only
ReiserFSOffline onlyOffline and online
ext2/3Offline onlyOffline only
SWAPFSOffline onlyOffline only
OpenGFSNoOnline only
NTFSOffline onlyOffline only

You can perform all of the supported shrink and expand operations with each of the EVMS user interfaces.