Enable Hibernation Option on Linux Mint 20

At first glance, one would be tempted to simply expand an existing a /swapfile as generated by Linux Mint installation defaults. Although that may be helpful in allocating more storage as augments for physical RAM, such /swapfile cannot be used toward hibernation resumes. A device or partition is required for hibernation to work correctly. Hence, these are the 2 options as prerequisites to enabling hibernation:

  1. Add a new physical disk as dedicated toward hibernation. When dealing with virtual machines, this would be the obvious choice.
  2. Resize an existing partition to reallocate storage toward a new partition. This is a risky move that could render the original partition as broken in worst-case scenarios.

Given the explanations above, we shall proceed with demonstrating this configuration.

Part 1: Enable hibernation menus and setting system to bypass memory checking

# Create the option to hibernate
sudo tee /etc/polkit-1/localauthority/90-mandatory.d/enable-hibernate.pkla <<'EOF'
[Enable hibernate]

# Obtain path of systemd-logind.service
kim@kim-linux:~$ systemctl show -p FragmentPath systemd-logind.service

# Insert Line after [Service] to bypass memory checking
sudo sed -i '/^\[Service\].*/a Environment=SYSTEMD_BYPASS_HIBERNATION_MEMORY_CHECK=1' /lib/systemd/system/systemd-logind.service

# Restart systemd-logind
sudo systemctl restart systemd-logind
sudo systemctl daemon-reload

kim@kim-linux:~$ systemctl restart systemd-logind
Warning: The unit file, source configuration file or drop-ins of systemd-logind.service changed on disk. Run 'systemctl daemon-reload' to reload units.

Part 2: Add a swap partition

# Discover physical disks on the system
root@kim-linux:/home/kim# lsblk -ido KNAME,TYPE,SIZE,MODEL
loop0 loop  97.9M 
sda   disk  14.9G KINGSTON_SNS4151S316GD
sdb   disk 232.9G Samsung_SSD_850_EVO_250GB

# List the partitions
root@kim-linux:/home/kim# parted -l
Error: /dev/sda: unrecognised disk label
Model: ATA KINGSTON SNS4151 (scsi)                                        
Disk /dev/sda: 16.0GB
Sector size (logical/physical): 512B/512B
Partition Table: unknown
Disk Flags: 

Model: ATA Samsung SSD 850 (scsi)
Disk /dev/sdb: 250GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 

Number  Start   End    Size   File system  Name                  Flags
 1      1049kB  538MB  537MB  fat32        EFI System Partition  boot, esp
 2      538MB   250GB  250GB  ext4

# Initiating partitioning process
root@kim-linux:/home/kim# sudo parted /dev/sda
GNU Parted 3.3
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.

# Create partitioning table as 'gpt'
(parted) mklabel gpt

# Create primary partition using the entire disk
(parted) mkpart primary swap 0% 100% # Correct command would be mkpart primary linux-swap 0% 100%
parted: invalid token: linux-swap
# Check result
(parted) print                                                            
Model: ATA KINGSTON SNS4151 (scsi)
Disk /dev/sda: 16.0GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags: 
Number  Start   End     Size    File system  Name     Flags
 1      1049kB  16.0GB  16.0GB               primary

# Exit partitioning program
(parted) quit
Information: You may need to update /etc/fstab.

# Alternative command to perform the steps above as 1-liner, assuming gpt has been set on a disk without any partitions
parted -a optimal /dev/sda mkpart primary '0%' '100%'

# Check disk partitions
root@kim-linux:/home/kim# lsblk                                           
loop0    7:0    0  97.9M  1 loop /snap/core/10583
sda      8:0    0  14.9G  0 disk 
└─sda1   8:1    0  14.9G  0 part 
sdb      8:16   0 232.9G  0 disk 
├─sdb1   8:17   0   512M  0 part /boot/efi
└─sdb2   8:18   0 232.4G  0 part /

# Set swapfile variable - be certain that a valid value is given here
# In this example: /dev/sda1 has been formatted as swap prior to this
# Zero out first 16MB of disk to effectively clear its partitioning table
sudo dd if=/dev/zero of=$swapPartition count=4096 bs=4096
# Set appropriate permissions to secure the directory
chmod 600 $swapPartition 
# Create swapfile in the swapPartition directory
mkswap $swapPartition
#configure system to use $swapfile
swapon $swapPartition 
# Check swapPartition settings
swapon -s

root@kim-linux:/home/kim# swapon -s
Filename				Type		Size	Used	Priority
/swapfile                              	file    	16777212	0	-2
/dev/sda1                              	partition	15637500	0	-3
# Enable swapPartition to persist reboots
sudo echo "$swapPartition swap swap sw 0 0" >> /etc/fstab
# Check fstab
cat /etc/fstab

Part 3: replace swap file with swap partition

# Check for existence of swap files and partitions
root@kim-linux:/home/kim# swapon -s
Filename				Type		Size	Used	Priority
/swapfile                              	file    	16777212	0	-2
/dev/sda1                              	partition	15637500	0	-3

# Comment out /swapfile usage as hibernation cannot work with it
sed '/^#/! {/swapfile/ s/^/#/}' -i /etc/fstab

# Remove the /swapfile
rm /swapfile

# Restart swapping engine
swapPartition=/dev/sda1 # Specify swap partition
swapoff -a # turn off swapping
swapon $swapPartition # direct engine to use given swap partition

Part 4: enable startup resuming process to retrieve saved session and fix grub os_prober bug

# Unique identifier (UUID) is a 128 bit number of 32 hexadecimal digits, a constant value used to name partitions in Linux operating systems. Since this value is a property of the partition, it can be transferred to different systems without loosing data. Target systems often automatically create hard links as mount points (e.g. /dev/sda1) toward the partition's UUID. It's recommended that the UUID value is being used on system resuming, instead of partitioning mount points.

# Discover the swap partition's UUID by correlating discovered disks to mounted IDs
root@kim-linux:/home/kim# ls -l /dev/disk/by-uuid
total 0
lrwxrwxrwx 1 root root 10 Jan 17 16:53 2e561ffb-fc38-4a2f-a7e3-f72659fff171 -> ../../sda1
lrwxrwxrwx 1 root root 10 Jan 17 16:09 4249-C724 -> ../../sdb1
lrwxrwxrwx 1 root root 10 Jan 17 16:09 de2a0dd7-1aea-4db2-a62d-0bc739646c8e -> ../../sdb2

# Set resume to retrieve saved sessions from the swap partition
sudo su
sed -i '/^GRUB_CMDLINE_LINUX_DEFAULT=*/ c\GRUB_CMDLINE_LINUX_DEFAULT=\"quiet splash resume='"$swapUuid"'\"' /etc/default/grub

# Fix grub boot delays
# Comment out last matching line of 30_os-prober (a bug)
lastMatchLineNumber=$(grep -n 'adjust_timeout' "$file" |tail -1|cut -f1 -d':')
sed -e "$lastMatchLineNumber s/^#*/#/" -i $file

# Edit grub
sudo vim /etc/default/grub
##### Set content similar to this #####
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash resume=/dev/disk/by-uuid/2e561ffb-fc38-4a2f-a7e3-f72659fff171"

# Update grub
sudo update-grub
sudo update-grub2
sudo update-initramfs -u

# Test Hibernation
sudo systemctl hibernate

The following steps deal with swap files, which is NOT helpful with hibernation. These are included here as reminder.

# Attempt to trigger hibernation
kim@kim-linux:~$ systemctl hibernate
Failed to hibernate system via logind: Not enough swap space for hibernation

# Check memory & swap
kim@kim-linux:~$ free -m
              total        used        free      shared  buff/cache   available
Mem:          32016        4179       24991        1204        2845       26243
Swap:          2047           0        2047

# Increase swap to 16GB
swapoff -a # turn off swapping
sudo dd if=/dev/zero of=/swapfile bs=1M count=16384 # copying zeros to swap with data size of 16GiB
sudo chmod 600 /swapfile # set correct permissions
sudo mkswap /swapfile # create swapfile
swapon -a # turn on swapping

# Check swapfile location
root@kim-linux:/home/kim# cat /etc/fstab
# /etc/fstab: static file system information.
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
# / was on /dev/sda2 during installation
UUID=de2a0dd7-1aea-4db2-a62d-0bc739646c8e /               ext4    errors=remount-ro 0       1
# /boot/efi was on /dev/sda1 during installation
UUID=4249-C724  /boot/efi       vfat    umask=0077      0       1
/swapfile                                 none            swap    sw              0       0
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