I recently made a basic Ubuntu VM with only 20GB of hard disk space and assumed I would only use it for light testing. As time went on, though, I eventually got the point where I wanted to install REMnux and SIFT on that box rather than create a whole new VM and space was becoming an issue.

So, I began by deleting all snapshots and increasing the VM size settings by 40GB. However, this new space was still marked “unallocated” and wasn’t automatically added to the existing partition. After a lot of trial and error, this is what ended up working for me:

  1. Run fdisk to begin a log of changes to be made. 
    $ sudo fdisk /dev/sda
  2. List all partitions using the p command. Note that the new 40GB is nowhere to be found in the list. Also, /dev/sda2 is an extended partition that contains the logical partition /dev/sda5. 
    Command (m for help): p
Device     Boot   Start      End  Sectors  Size Id Type
/dev/sda1  *       2048  1050623  1048576  512M  b W95 FAT32
/dev/sda2       1052670 41940991 40888322 19.5G  5 Extended
/dev/sda5       1052672 41940991 40888320 19.5G 83 Linux
  3. Delete the partitions I want to expand 
    Command (m for help): d
Partition number (1,2,5, default 5): 5
Partition 5 has been deleted.
Command (m for help): d 
Partition number (1,2, default 2): 2
Partition 2 has been deleted.
  4. Create partition 2 (with default settings) to cover all available space. 
    Command (m for help): n   
Partition type   
p   primary (1 primary, 0 extended, 3 free)   
e   extended (container for logical partitions)
Select (default p): e
Partition number (2-4, default 2): 2
First sector (1050624-125829119, default 1050624): 
Last sector, +/-sectors or +/-size{K,M,G,T,P} (1050624-125829119, default 125829119): 
Created a new partition 2 of type 'Extended' and of size 59.5 GiB.
  5. Create logical partition 5 (with default settings). 
    Command (m for help): n
All space for primary partitions is in use.
Adding logical partition 5
First sector (1052672-125829119, default 1052672): 
Last sector, +/-sectors or +/-size{K,M,G,T,P} (1052672-125829119, default 125829119): 
Created a new partition 5 of type 'Linux' and of size 59.5 GiB.
Partition #5 contains a ext4 signature.
Do you want to remove the signature? [Y]es/[N]o: Y
The signature will be removed by a write command.

  6. Finally, enter w to write the logged changes and sudo reboot to restart the VM.

  7. Once the machine is rebooted, resize2fs will need to be run against the logical partition to finalize the changes. 
    sudo resize2fs /dev/sda5
resize2fs 1.45.5 (07-Jan-2020)
Filesystem at /dev/sda5 is mounted on /; on-line resizing required
old_desc_blocks = 3, new_desc_blocks = 8
The filesystem on /dev/sda5 is now 15597056 (4k) blocks long.