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Create swap file in Ubuntu

#ubuntu

Create a swap file to let OS use when the physical memory is not big enough. Make the swap file as 1~2x big as your physical memory.

How much swap size do you need

Based on your physical memory size, here is a chart you can use:

  • 1G -> 2G
  • 4G -> 6G
  • 6G -> 8G
  • 8G -> 11G
  • 16G -> 20G
  • 32G -> 38G

Create swap file

CreateSwap.sh:

#!/usr/bin/env bash fallocate -l 12G /swapfile chmod 600 /swapfile mkswap /swapfile swapon /swapfile echo "/swapfile swap swap defaults 0 0" >> /etc/fstab
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Then use swapon --show to check current swaps.

If your system already configured other swaps, you can use swapoff to remove it, for example:

swapoff /dev/sdb
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Also remember to remove it in the /etc/fstab file such that it won't get used when system rebooted next time.

Reference

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peter279k •

We can also use the parted command to create the swap partition.

Here are examples to do that:

pi@raspberrypi:~ $ free -mh total used free shared buff/cache available Mem: 7.7Gi 369Mi 6.8Gi 24Mi 579Mi 7.1Gi Swap: 99Mi 0B 99Mi pi@raspberrypi:~ $ sudo parted (parted) print free Model: SD SD (sd/mmc) Disk /dev/mmcblk0: 62.1GB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags: Number Start End Size Type File system Flags 16.4kB 4194kB 4178kB Free Space 1 4194kB 273MB 268MB primary fat32 lba 2 273MB 31.9GB 31.6GB primary ext4 31.9GB 62.1GB 30.2GB Free Space (parted) mkpart primary linux-swap Start? 31.9GB End? 44GB (parted) print free Model: SD SD (sd/mmc) Disk /dev/mmcblk0: 62.1GB Sector size (logical/physical): 512B/512B Partition Table: msdos Disk Flags: Number Start End Size Type File system Flags 16.4kB 4194kB 4178kB Free Space 1 4194kB 273MB 268MB primary fat32 lba 2 273MB 31.9GB 31.6GB primary ext4 31.9GB 31.9GB 524kB Free Space 3 31.9GB 44.0GB 12.1GB primary linux-swap(v1) lba 44.0GB 62.1GB 18.1GB Free Space (parted) Information: You may need to update /etc/fstab. pi@raspberrypi:~ $ sudo mkswap /dev/mmcblk0p3 Setting up swapspace version 1, size = 11.3 GiB (12084834304 bytes) no label, UUID=d89e85d9-e8be-470f-9c67-86648cc590f7 pi@raspberrypi:~ $ sudo swapon /dev/mmcblk0p3 pi@raspberrypi:~ $ free -mh total used free shared buff/cache available Mem: 7.7Gi 377Mi 6.9Gi 24Mi 427Mi 7.1Gi Swap: 11Gi 0B 11Gi pi@raspberrypi:~ $ pi@raspberrypi:~ $ echo "UUID=d89e85d9-e8be-470f-9c67-86648cc590f7 swap swap defaults 0 0" | sudo tee -a /et c/fstab UUID=d89e85d9-e8be-470f-9c67-86648cc590f7 swap swap defaults 0 0 pi@raspberrypi:~ $ cat /etc/fstab proc /proc proc defaults 0 0 PARTUUID=a2dee777-01 /boot vfat defaults 0 2 PARTUUID=a2dee777-02 / ext4 defaults,noatime 0 1 # a swapfile is not a swap partition, no line here # use dphys-swapfile swap[on|off] for that UUID=d89e85d9-e8be-470f-9c67-86648cc590f7 swap swap defaults 0 0
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