[linux-lvm] dynamic allocation

[Corin Langosch]

Hi!

I'm using lvm2. Currently I have on big VG (100GB) and several LV for 
VServers each 20GB. So my system is limited to having 5 Vservers.

Is it possible to tell lvm2 to start with only little allocation and 
dynamically grow the LV? I know I can grow it using the command line 
tools but I want it to happen fully automatically.

So in terms of comands something like:
lvcreate --size-max 20GB --size-grow 100MB --size-start 1GB vserver06 data

So the LV would intitially allocate only 1GB of the VG and allocate new 
space in 100MB as it needs, stopping at a maximum size of 20GB. Of 
course I would then have to make sure the VG has enough free blocks for 
the LVs to grow, but that shouldn't be a problem.

I think this should technically be possible as software like VirtualBox 
can grow it's image file the same way to. If lvm can't to that, could 
that be done with some kind of loopback device? Which is the best way 
(also in terms of performance) to handle such a setup?

Best regards,
Corin