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How to identify and delete old Ubuntu partitions

rated 0 times [ 1] [ 0] / answers: 1 / hits: 924 / 2 Years ago, sun, june 19, 2022, 5:56:08

I have a computer with two internal hard disks. Initially, Ubuntu 16.04 was installed. I installed Ubuntu 20.04 on the other hard disk so I could gradually migrate everything. I have finished the migration and and happy with 20.04 and am ready to delete the partitions used for 16.04. But I am very inexperienced and nervous about doing this, so am asking here for the precise steps to take so that I don't screw up my 20.04 installation.
Here are the current partitions:

/dev/sdb - where 16.04 was initially installed

    /dev/sdb1 - EFI System; 537 MB; FAT32

    /dev/sdb2 - Ext4; 991 GB (encrypted)

    /dev/sdb3 - Swap  

/dev/sda - where 20.04 was installed

    /dev/sda1 - EFI System; 537 MB; FAT32

    /dev/sda2 - Ext4; 991 GB (not encrypted)

I obviously want to keep /dev/sda2 and want to replace the encrypted /dev/sdb2 with some other partition. I have no idea what to do about the two EFI partitions. I presume, but am not entirely sure, that the Swap partition is being used by both 16.04 and 20.04, so it should be left alone.
So, any help in the precise applications and steps to use to achieve my goal, which is to completely remove 16.04 and boot directly to 20.04, would be very much appreciated.
Additional diagnostic info:

    free -h

          total        used        free      shared  buff/cache   available

    Mem:           15Gi       2.3Gi       4.1Gi       878Mi       9.1Gi        12Gi

    Swap:         2.0Gi          0B       2.0Gi



    swapon -s

    Filename                Type        Size    Used    Priority

    /swapfile                               file        2097148 0   -2



    grep -i swap /etc/fstab

    /swapfile                                 none            swap    sw              0       0



    df | grep -v loop

    Filesystem     1K-blocks      Used Available Use% Mounted on

    udev             8092712         0   8092712   0% /dev

    tmpfs            1627296      1944   1625352   1% /run

    /dev/sda2      959863856 375460708 535574940  42% /

    tmpfs            8136472    641684   7494788   8% /dev/shm

    tmpfs               5120         4      5116   1% /run/lock

    tmpfs            8136472         0   8136472   0% /sys/fs/cgroup

    /dev/sda1         523248      7944    515304   2% /boot/efi

    tmpfs            1627292        64   1627228   1% /run/user/1000

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answered 2 Years ago hreadsoplet · Accepted Answer

The goal: remove 16.04 and unneeded partitions.

Note: Have good backups before changing anything.

Note: Answer based on given data. If incorrect data, then this answer would be incorrect.

Since:

/dev/sda is your current running 20.04 system

the swap on /dev/sdb3 is not being used by 20.04

the /swapfile on /dev/sda2 is being used by 20.04

/dev/sda1 is the EFI partition used by 20.04

/dev/sdb1 - /dev/sdb3 were being used by 16.04

You can:

Just wipe /dev/sdb by using gparted and laying down a fresh GPT partition table on /dev/sdb. Recreate new partitions as desired.

/swapfile

I'd recommend increasing your /swapfile from 2G to 4G.

Note: Incorrect use of the dd command can cause data loss. Suggest copy/paste.

sudo swapoff -a           # turn off swap

sudo rm -i /swapfile      # remove old /swapfile



sudo dd if=/dev/zero of=/swapfile bs=1M count=4096



sudo chmod 600 /swapfile  # set proper file protections

sudo mkswap /swapfile     # init /swapfile

sudo swapon /swapfile     # turn on swap

free -h                   # confirm 16G RAM and 4G swap

Confirm this line in /etc/fstab... and confirm no other “swap” lines...

/swapfile    none    swap    sw      0   0

reboot                    # reboot and verify operation