This guide will walk you through the steps required to grow a partition in Linux. You will have to reboot through this guide.
- If possible, make a snapshot.
Often, you will want to grow the partition table because you made your virtual hard disk too small, and you tried to extend it in your hypervisor, only to find out that your partition is still the same size as it was before.
This process should be completely safe, but just make a snapshot anyway. Since you're probably on a hypervisor, making a snapshot is easy and cheap. Do it.
-
Use gdisk(8) to grow your partition table (fdisk can't)
% sudo gdisk /dev/sda GPT fdisk (gdisk) version 1.0.1 Partition table scan: MBR: protective BSD: not present APM: not present GPT: present Found valid GPT with protective MBR; using GPT. Command (? for help): w Warning! Secondary header is placed too early on the disk! Do you want to correct this problem? (Y/N): Y Have moved second header and partition table to correct location. Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING PARTITIONS!! Do you want to proceed? (Y/N): Y OK; writing new GUID partition table (GPT) to /dev/sda. Warning: The kernel is still using the old partition table. The new table will be used at the next reboot or after you run partprobe(8) or kpartx(8) The operation has completed successfully.
You don't have to reboot. Yet...
-
Take note of your existing partition
% sudo gdisk /dev/sda GPT fdisk (gdisk) version 1.0.1 Partition table scan: MBR: protective BSD: not present APM: not present GPT: present Found valid GPT with protective MBR; using GPT. Command (? for help): p Disk /dev/sda: 629145600 sectors, 300.0 GiB Logical sector size: 512 bytes Disk identifier (GUID): 81E5985B-444C-4D94-80D5-C5B863B4F400 Partition table holds up to 128 entries First usable sector is 34, last usable sector is 204799966 Partitions will be aligned on 8-sector boundaries Total free space is 2015 sectors (1007.5 KiB) Number Start (sector) End (sector) Size Code Name 1 2048 4096 1024.5 KiB EF02 primary 2 4098 204799966 97.7 GiB 8E00 primary Command (? for help): d
You must write down (or keep in our scrollback) that our partition has Start
sector 4098 and Code 8E00. You will need these values later on.
- Use gdisk(8) to grow your partition (fdisk can, but gdisk is better)
Here you will remove the partition and re-create it using a new Last sector, which is bigger than the previous.
When being asked for the Last sector, simply press Enter to get the largest value.
WARNING If you get the message Information: Moved requested sector,
STOP WHAT YOU ARE DOING, PRESS ^C IMMEDIATELY. Read further ahead.
Command (? for help): d
Partition number (1-2): 2
Command (? for help): n
Partition number (2-128, default 2): 2
First sector (34-629145566, default = 4097) or {+-}size{KMGTP}: 4098
Last sector (4098-629145566, default = 629145566) or {+-}size{KMGTP}: 629143552
Current type is 'Linux filesystem'
Hex code or GUID (L to show codes, Enter = 8300): 8E00
Changed type of partition to 'Linux LVM'
Command (? for help): p
Disk /dev/sda: 629145600 sectors, 300.0 GiB
Logical sector size: 512 bytes
Disk identifier (GUID): 81E5985B-444C-4D94-80D5-C5B863B4F400
Partition table holds up to 128 entries
First usable sector is 34, last usable sector is 629145566
Partitions will be aligned on 1-sector boundaries
Total free space is 4029 sectors (2.0 MiB)
Number Start (sector) End (sector) Size Code Name
1 2048 4096 1024.5 KiB EF02 primary
2 4098 629143552 300.0 GiB 8E00 Linux LVM
Command (? for help): w
Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING
PARTITIONS!!
Do you want to proceed? (Y/N): Y
OK; writing new GUID partition table (GPT) to /dev/sda.
Warning: The kernel is still using the old partition table.
The new table will be used at the next reboot or after you
run partprobe(8) or kpartx(8)
The operation has completed successfully.
- Reboot your machine
As gdisk already told you, the kernel is still using the old partition table. Since there are mounted filesystems on it, it refuses to reload it, so you'll have to reboot. This is safe to do if you've completed step 4 without writing any number wrong. 😈
- Resize your filesystem
When you've booted back into your system, you'll notice that you can't utilize your newly created space. You must tell your filesystem explicitly to do so.
If you use LVM (after this you must still resize the actual filesystem):
pvresize /dev/sda2
lvextend -l 100%VG /dev/mapper/root
If you use ext234 (use the /dev/mapper thingy if it's under LVM):
resize2fs /dev/sda2
If you use XFS (use the /dev/mapper thingy if it's under LVM):
xfs_growfs /dev/sda2
If you get the Information: Moved requested sector message, STOP.
Check your numbers. Did you make a typo? That's okay. As long as you don't
write using w nothing bad has happened yet. Abort with ^C. Start again.
If your numbers DO match, you have a strange partition setup. This may happen especially if you didn't install Linux by hand, but used some orchestrator to make your life easier. All magic has a price, and now you must pay.
gdisk will not allow you to set the partition back the way it was, because in 99.98% of all cases it would be a REALLY BAD IDEA™ to do so. But you're different. Lucky you. Especially for snowflakes like you, gdisk has so-called extra functionality or expert menu. Here, you can set gdisk's sector alignment value, which really just means that every sector must be dividable by this number. For modern harddisks, this number is 2048.
We will set the sector alignment value to 1 (one), since every integer
is dividable by one, it will allow you to set any weird number you want.
% sudo gdisk /dev/sda
GPT fdisk (gdisk) version 1.0.1
Partition table scan:
MBR: protective
BSD: not present
APM: not present
GPT: present
Found valid GPT with protective MBR; using GPT.
Command (? for help): x
Expert command (? for help): l
Enter the sector alignment value (1-65536, default = 2048): 1
Expert command (? for help): m
Don't quit gdisk now, or you'll have to do these steps again.
From here, you can use gdisk as usual, so now you can continue where step 4 left
off. You should NOT get the Information: Moved requested sector message
this time.