How to grow filesystem to use unallocated space in partition? I duplicated a hard disk to a new larger one using the method suggested in Full DD copy from hdd to hdd. After doing that `df -h` reports the original and smaller partition sizes from the original disk and `gparted` highlights the disparity and offers to fix them, though it seems unwise as they are mounted. If you look closely at the image you can see that `Used + Unused < Size` for the partitions with the yellow warning signs. What command line tools can be used to fix the issue, and will it be safe for `gparted` to do it on mounted partition live? Ideally I should have done that before switching over to the target disk and rebooting from it. ![Gparted Snapshot]( Below is the information dialog from gparted about the discrepancy and I edited the title to describe it better. ![Gparted information dialog](

* If `gparted` only has to extend the partition or filesystem into unused space (immediately following the partition), then it should be safe to let it extend the partition and/or fs.

* If, however, it has to MOVE any partitions around to make space for resizing, you'll have to boot with a gparted Live CD

* See the man page for `resize2fs` (which is the command-line tool gparted will use to grow an ext2, ext3, and ext4 filesystem) for more details about resizing those filesystems.

For ext2/3/4, growing a filesystem is generally not a problem and can safely be done while the fs is mounted.

Shrinking a filesystem, however, is more troublesome and should be done while the fs is unmounted. If it's the rootfs, that means booting to a rescue CD/USB/PXE etc.




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BTW, both `dd` and `cat` are amongst the worst ways to copy a linux system to another hard disk. Use Clonezilla, that's what it's for.