Resize Ubuntu /dev/sda1 partition in VirtualBox VMDK when /dev/sda is already larger

Question

Some time ago I created a VMDK which was mapped to a raw partition on a SSD.

The SSD was a 128GB one, I partitioned it in Windows (the host), made the second partition accessible to Windows (NTFS), and used the first partition to map it into a VMDK.

This first partition has a size of about 48GB.

When I then installed Ubuntu Server in a VM which used that VMDK, I noticed that the size of /dev/sda shown to me was the 128GB, but I created the partition during the Ubuntu installation to be of the size of the first partition, so that /dev/sda1 is of 48GB.

Due to the lack of space on /dev/sda1 (there are 5GB free) I bought another SSD, and decided to stop using raw mappings. I copied the VMDK via the Virtual Media Manager onto the new SSD, so there I now have a VMDK file of aprox. 44GB (don't take it very exactly, it's the MiB vs GiB vs GB issue).

I thn replaced the HDD of the VM with the newly copied VMDK and booted it. It works as expected.

Now I have this:

:~$ cat /proc/partitions
major minor  #blocks  name

  11        0      58100 sr0
   8        0  125034840 sda
   8        1   46873600 sda1
   8       16  488386584 sdb
   8       17  181189085 sdb1

this

~$ sudo fdisk -l
Disk /dev/sda: 119.2 GiB, 128035676160 bytes, 250069680 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x000271d1

Device     Boot Start      End  Sectors  Size Id Type
/dev/sda1  *     2048 93749247 93747200 44.7G 83 Linux


Disk /dev/sdb: 465.8 GiB, 500107862016 bytes, 976773168 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 59B4B505-C79F-11E3-8F9C-709E29CA19D2

Device     Start       End   Sectors   Size Type
/dev/sdb1     34 362378204 362378171 172.8G Linux filesystem

and this

:/$ df -h
Filesystem       Size  Used Avail Use% Mounted on
udev             7.9G     0  7.9G   0% /dev
tmpfs            1.6G  9.1M  1.6G   1% /run
/dev/sda1         44G   37G  5.1G  88% /
tmpfs            7.9G  1.1M  7.9G   1% /dev/shm
tmpfs            5.0M     0  5.0M   0% /run/lock
tmpfs            7.9G     0  7.9G   0% /sys/fs/cgroup
windows-avconv   1.9T  1.8T  103G  95% /home/user/windows-avconv
windows-storage  1.9T  1.8T  103G  95% /home/user/windows-storage
windows-share     50G  101M   50G   1% /home/user/windows
cgmfs            100K     0  100K   0% /run/cgmanager/fs
/dev/sdb1        170G   91G   72G  56% /media/hdd
tmpfs            1.6G     0  1.6G   0% /run/user/1000

All of this seems to indicate that I can just issue a

sudo resize2fs /dev/sda1

and then /dev/sda1 will grow to become 119.2 GiB big without me needing to use VBoxManage modifyhd <absolute path to file> --resize <size in MB>

Am I correct with this assumption?

---

Update: I made a backup copy of the VMDK and issued a

:~$ sudo resize2fs /dev/sda1

This is the result:

resize2fs 1.42.13 (17-May-2015)
The filesystem is already 11718400 (4k) blocks long.  Nothing to do!

Do I need to issue a

sudo growpart /dev/sda 1

before resize2fs can work?

Answer 1

You have to first resize the partition with the following steps:

1. sudo parted /dev/sda to enter the prompt "(parted)" as the superuser
2. resizepart 1 to resize the partition 1
3. -0 resizes it to the end of the disk. - indicates that it should count from the end of the disk, not the start. This makes -0 the last sector of the disk - which is suitable when you want to make it as big as possible. Step 4:
4. quit to exit parted

The file system meta information needs to indicate the size of disk, and resize2fs updates this. Thus, after expanding, run resize2fs /dev/sda1.

It's highly recommended to do this in either single user mode / recovery mode, or with the file system mounted in read only mode. You can mount it read only by mount -o remount,ro /dev/sda1.

Extending is possible to do with filesystem in RW-mode, but it increases chances of data loss. As this is a VM, and you can easily make a backup, doing it with the volume mounted RW may make sense.

Addendum: run commands as root for desired effect.