Coming from Solaris, the AIX Logical Volume Manager can be a bit confusing at first. With AIX you get something similar to Veritas Volume Manager built into the operating system : much more powerful than disk partitions. However, it can be a bit hard to get your head round at first.
AIX assigns sensible low values to filesystems (the equivalent of partitions) during the installation. You are free to increase the size of filesystems, which you can do online dynamically : smit chfs or with the command
chfs -a size=+<size> <filesystem>
e.g chfs -a size=+200M /usr
. If you install additional software and /usr fills up, AIX will automatically increase the size of /usr during the software installation so everything fits on.
So in AIX you have :
- volume groups (often called disk groups in other OSs) : a group of physical disks, lumped together to give you a big space to spread files across. Volume groups (with the exception of rootvg) can easily be moved from one server to another and shared between multiple servers, all as part of thebasic OS functionality.
- logical volumes : containers, in which you can put filesystems, paging (swap) space, boot logical volume and dump devices. You can also define a raw logical volume for a database to access directly. These are the equivalent of disk partitions, but much better. They can increase size dynamically (paging spaces can be shrunk too); they can be spread across multiple disks, mirrored and striped very easily through smit. You can break off a copy of a logical volume (e.g. to do a backup) and then remerge it later. You can move a logical volume from one disk to another while the system is running normally.
Everything can be done through smit (type "smit lvm" for the volume group/logical volume things and "smit fs" for filesystems) or on the command line (smit saves the commands it runs to ~/smit.script).
In addition to the commands crabboy mentions, here some some others you might find useful :
lspv hdisk0 : overview of disk
lspv -l hdisk0 : list logical volumes of hdisk0
lslv -m hd5 : list the location of every partition in hd5
lsvg -p rootvg : list physical disks in rootvg
lsvg -l rootvg : list logical volumes in rootvg
lsvg rootvg : overview of rootvg
You might it useful to take a look at www.rootvg.net
which has a link to a chart comparing commands from different OSs including (I think) AIX and Solaris.