ext3 поддерживает увеличение раздела на лету:
RESIZE2FS(8) RESIZE2FS(8)
NAME
resize2fs - ext2/ext3/ext4 file system resizer
SYNOPSIS
resize2fs [ -fFpPM ] [ -d debug-flags ] [ -S RAID-stride ] device [
size ]
DESCRIPTION
The resize2fs program will resize ext2, ext3, or ext4 file systems. It
can be used to enlarge or shrink an unmounted file system located on
device. If the filesystem is mounted, it can be used to expand the
size of the mounted filesystem, assuming the kernel supports on-line
resizing. (As of this writing, the Linux 2.6 kernel supports on-line
resize for filesystems mounted using ext3 only.).