How can I move / to a different partition on the same disk with lvm?

Ask Fedora
1

This might be the simplest way to illustrate what I would like to achieve.
I have this:
It has a 70G partition for / and I am getting lots of disk full errors (mostly /tmp)

nvme0n1                259:0    0   1.8T  0 disk 
├─nvme0n1p1            259:1    0   600M  0 part /boot/efi
├─nvme0n1p2            259:2    0     1G  0 part /boot
└─nvme0n1p3            259:3    0   1.8T  0 part 
  ├─rl_wintermute-root 253:0    0    70G  0 lvm  /
  ├─rl_wintermute-swap 253:1    0  15.6G  0 lvm  [SWAP]
  └─rl_wintermute-home 253:2    0   1.7T  0 lvm  /home

How do I achieve this:

nvme0n1                259:0    0   1.8T  0 disk 
├─nvme0n1p1            259:1    0   600M  0 part /boot/efi
├─nvme0n1p2            259:2    0     1G  0 part /boot
└─nvme0n1p3            259:3    0   1.8T  0 part 
  ├─rl_wintermute-swap 253:1    0  15.6G  0 lvm  [SWAP]
  └─rl_wintermute-home 253:2    0   1.7T  0 lvm  /home
                                                 /

With / and /home on the same partition, thereby putting the whole works
on one partition, and allowing me to use the entire disk for everything.

2

/tmp is not stored on disk (unless you changed the default configuration) but on a tmpfs which is stored in memory. If you are regularly running out of place in /tmp you are doing something wrong. You should probably look into storing your temporary files in your /home or /var/tmp (or configure whatever application is saving a lot of data to /tmp to store it elsewhere).

That might be quite hard without reinstalling unfortunately (depending on how much free space do you have in your /home currently). What filesystem do you use? If it’s ext4 which supports shrinking, then adding more space to your / will be trivial, but if you are using xfs, which doesn’t support shrinking, you might need to reinstall.

1 Like
3

But they are already in one partition. nvme01n1p3 is the partition and this is the PV for the volume group.
How much space is still available in the home LV ?
df -Th

Maybe you could shrink rl_wintermute-home by X amount of GB ( if the filesystem is ext4 ) and extend rl_wintermute-root. Easiest would be to remove swap or shrink swap and extend rl_wintermute-root.
LVM makes much more sense if you keep free extends available.. These extends can be assigned to a LV anytime when required.

4

Ugh… I am hopeless with filesystems, I think. Every time I think I understand something, I find out that something else is keeping me from understanding what I thought I knew.

$ df -Th
Filesystem                     Type      Size  Used Avail Use% Mounted on
devtmpfs                       devtmpfs  4.0M     0  4.0M   0% /dev
tmpfs                          tmpfs      32G   17M   32G   1% /dev/shm
tmpfs                          tmpfs      13G   21M   13G   1% /run
efivarfs                       efivarfs  128K   18K  106K  15% /sys/firmware/efi/efivars
/dev/mapper/rl_wintermute-root xfs        70G   68G  2.7G  97% /
/dev/mapper/rl_wintermute-home xfs       1.8T  1.3T  502G  72% /home
/dev/nvme0n1p2                 xfs       960M  650M  311M  68% /boot
/dev/nvme0n1p1                 vfat      599M  7.1M  592M   2% /boot/efi
/dev/sda1                      ext4      1.8T  1.5T  290G  84% /mnt/bakhdd
/dev/sdb1                      ext4      5.5T  3.1T  2.1T  60% /mnt/WinterStore
shalmaneser:/mnt/store/Lin_Win nfs4      3.7T  2.5T  1.2T  68% /home/sheldon/mnts/Lin_Win
shalmaneser:/mnt/store/Media   nfs4      3.7T  2.5T  1.2T  68% /home/sheldon/mnts/Movies
tmpfs                          tmpfs     6.3G   78M  6.2G   2% /run/user/1000

They are on the same PV (physical volume?) They are formatted with xfs. I am pretty much lost now. :slight_smile:

5

Sigh… They are all using xfs.

I didn’t change anything, that I know of, but I guess I must have. How can I change /tmp to be in my /home/tmp folder?

6

worse is the fact that 500GB are still free. Now imagine this LV with an initial size of 1.5TB leaving 300GB as a reserve of free extends waiting to be assigned to any LV in the VG with one command!

you can’t shrink xfs only via xfsdump and xfsrestore.