Situation: increase swap size (/dev/sda3
) greater than Ram (8 GB) when HD 128 GB
Motivation: 8 GB RAM is too little; 30 GB free space in my SSD; I want to turn 20 GB to SSD swap
Characteristics of system
-
Swap non-immutable/changeable. I cannot find any evidence why
/mnt/.swapfile
should be immutable so you do not need the change the file attributes of the swapfilesudo lsattr /mnt/.swapfile -------------e-- /mnt/.swapfile
-
Command
sudo fdisk -lu /dev/sda
givesDisk /dev/sda: 113 GiB, 121332826112 bytes, 236978176 sectors Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disklabel type: gpt Disk identifier: 082F85CA-EE3E-479C-8244-858B196FA5BA Device Start End Sectors Size Type /dev/sda1 2048 4095 2048 1M BIOS boot /dev/sda2 4096 220323839 220319744 105.1G Linux filesystem /dev/sda3 220323840 236976127 16652288 8G Linux swap
-
Command
df -h
givesFilesystem Size Used Avail Use% Mounted on udev 3.9G 0 3.9G 0% /dev tmpfs 793M 9.4M 784M 2% /run /dev/sda2 104G 74G 25G 75% / tmpfs 3.9G 54M 3.9G 2% /dev/shm tmpfs 5.0M 4.0K 5.0M 1% /run/lock tmpfs 3.9G 0 3.9G 0% /sys/fs/cgroup tmpfs 793M 64K 793M 1% /run/user/1000
-
Allocate more disk space for Swap in
/dev/sda3
.
My unsuccessful workflow for the task when HD and Swap on the same partition, /dev/sda3
masi@masi:~$ sudo -i
root@masi:~# swapoff /dev/sda3
root@masi:~# swapon
[blank]
root@masi:~# dd if=/dev/zero of=/dev/sda3 bs=20480 count=1M
dd: error writing '/dev/sda3': No space left on device
416308+0 records in
416307+0 records out
8525971456 bytes (8.5 GB, 7.9 GiB) copied, 18.7633 s, 454 MB/s
root@masi:~# mkswap /dev/sda3
Setting up swapspace version 1, size = 8 GiB (8525967360 bytes)
no label, UUID=245cb42c-1d4e-4e21-b544-16b64af962d6
root@masi:~# swapon -p 99 /dev/sda3
root@masi:~# swapon
NAME TYPE SIZE USED PRIO
/dev/sda3 partition 8G 0B 99
root@masi:~# vi /etc/fstab
...
HD and Swap on same Partition – Current Workflow [Ijaz, cas, FarazX]
Merging. Use fallocate
at the beginning instead dd
because no need to put zeros
masi@masi:~$ sudo fallocate -l 20G /mnt/.swapfile
masi@masi:~$ sudo mkswap /mnt/.swapfile
Setting up swapspace version 1, size = 20 GiB (21474832384 bytes)
no label, UUID=45df9e48-1760-47e8-84d7-7a14f56bbd72
masi@masi:~$ sudo swapon /mnt/.swapfile
swapon: /mnt/.swapfile: insecure permissions 0644, 0600 suggested.
masi@masi:~$ sudo chmod 600 /mnt/.swapfile
masi@masi:~$ free -m
total used free shared buff/cache available
Mem: 7925 1494 175 196 6255 5892
Swap: 28610 0 28610
Add the following line in your /etc/fstab
which is better than adding the thing to your runlevels (/etc/rc.local
), where I put the swapfile to the /mnt/.swapfile
to maintain Linux/Unix philosophy and maintain the integrity of my system backup scripts; If swapping to an SSD, use the discard
option so that the blocks are trimmed on every reboot, so not sw
# http://unix.stackexchange.com/a/298212/16920
# http://unix.stackexchange.com/a/298543/16920
# If swap is on SSD, trim blocks each time at startup.
/mnt/.swapfile none swap defaults,discard 0 0
# If swap on External HDD, just use sw.
#/media/masi/SamiWeek/.swapfile none swap sw 0 0
Sources
- How to increase swap space? https://askubuntu.com/a/178726/25388 General discussion about increasing swap space for beginners.
- Linux Partition HOWTO for HDDs, not SSDs: 4. Partitioning requirements. http://www.tldp.org/HOWTO/Partition/requirements.html So do not put your swap to outer tracks on SSDs but use
defaults,discard
options to trim your blocks as proposed by @cas.
System: Linux Ubuntu 16.04 64 bit
Linux kernel: 4.6
Linux modules: wl
Hardware: Macbook Air 2013-mid
Ram: 8 GB
SSD: 128 GB
Best Answer
You just want to increase the swap size on your system using the space from
sda2
. Yoursda2
You can add additional swap space to your system by using swap file created on
/
that will utilize yoursda2
. Just do:and then do:
and check, you swap space will increase by that amount using
free -m
and yes , to enable it at boot time add the entry in
/etc/fstab