swap article

content/blog/20240315-swap.md

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+---
+Title: Adding SWAP to a Debian Machine
+Description: Guide to remind myself how to add swap to Debian machines.
+Tags: 
+  - sysadmin
+
+---
+
+So for SWAP, we usually have two choices. A swapfile, and a swap partition.
+
+A swapfile is a lot more flexible since it lives on your filesystem. However, it
+does have an added overhead of the filesystem.
+
+Another reason why you may want to use a swap partition is that in case you have
+more than one linux distro installed, they can share the same swap partition.
+
+People also [encrypts their swap
+partition](https://askubuntu.com/questions/313564/why-encrypt-the-swap-partition)
+
+1. First we create the swapfile with 4G \
+`fallocate -l 4G /swapfile`
+
+2. Then, we set the correct permission for the swapfile \
+`chmod 600 /swapfile`
+
+3. We now run this to setup the swapfile with the correct headers. \
+`mkswap /swapfile`
+
+4. We will now run this to enable the swap partition, please note that this is a
+transient operation and will not persist if you reboot the system. \
+`swapon /swapfile`
+
+5. Lastly, we will add the swapfile to our fstab so it will automatically enable
+the swapfile on boot. \
+`echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab`
+
+There are also two sysctl options that you can tweak, either via the sysctl
+command (transient), or `/etc/sysctl.conf` (persistent).
+
+`vm.swappiness` \
+`vm.vfs_cache_pressure`
+
+Further reading: [kernel Memory Management
+docs](https://docs.kernel.org/admin-guide/mm/index.html)
+
+Adapted from the [DigitalOcean SWAP space
+guide](https://www.digitalocean.com/community/tutorials/how-to-add-swap-space-on-ubuntu-20-04)