When you blew last year’s budget on a brand new SAN, its potential seemed second only to its simplicity: As demand grows, add capacity from a huge storage pool, and never have to worry about individual hard drives again. When you increase the allocation to the Mac share, however, your workstations still see the same amount of space. Unlike Leopard, Mac OS X 10.4 can’t natively or dynamically increase partition size, and no version of Apple’s Disk Utility can resize NTFS or Linux partitions.

As files grow larger and storage more decentralized, managing Macintosh volumes on a shared network can be a significant challenge. Coriolis Systems’ iPartition meets that challenge by resizing populated file systems, growing and shrinking partitions without damaging their contents.

Simply select the “disk” you need to modify from the list on the left side of iPartition’s main window. This can be a literal disk, a local RAID array, or a designated slice from a logical volume device. Then grab the textured handle on your existing colored partition and drag it around until it eclipses the gray empty area entirely (or use the “Inspector” panel to specify the partition size down to the byte). Since this is a major disk operation, you’ll want to have a current backup of the partition just in case. You’ll also want to turn off network sharing to the volume before you proceed, since resizing it in this manner will unmount it momentarily.

Once you’re happy with your changes, hit the bright green “Go” button, and your changes will commit to disk (often instantaneously). If you assign too much space, you can shrink volumes in the same manner, though the process is much slower in reverse (you’d probably want to leave a 500GB volume overnight). There are a number of other disk management features (including a limited version of Coriolis’ iDefrag utility) in iPartition, but it’s ability to change filesystems of all types nondestructively that makes the program invaluable part of any administrator’s toolkit.

Update: Although Leopard added the ability resize HFS+ partitions dynamically, iPartition has only improved since our initial review, handling all categories of Volume beautifully on multi-OS storage systems. We wouldn’t maintain a network of any complexity without it.

iPartition retails for $49.95.