I found a very nice tutorial on how to create virtual hard disks, and I am considering using these for my work in order to store reliably and portably large datasets with associated processing results.
Basically, the tutorial consist in doing this:
dd if=/dev/zero of=MyDrive.vhd bs=1M count=500 mkfs -t ext3 MyDrive.vhd mount -t auto -o loop MyDrive.vhd /some/user/folder
which creates a virtual hard drive of 500MB formatted in ext3 and mounts it somewhere.
Now say I use that file and realise I need more than 500MB, is there a way of "dynamically" resizing the virtual disk? (By dynamically I mean other than creating a new bigger disk and copy the data over.)