Swap partition on SD card

Swap on SD card (same with USB thumdbrives) is a bad idea. So if you have to use a swap partition (if that's needed for hibernation -- no idea) you simply adjust "swappiness":

echo "vm.swappiness=0" >> /etc/sysctl.conf

This will lead to swap being used only in emergency situations any more (most likely never). Needs a reboot.

In case you're low an RAM (this does NOT affect your box with 8GB RAM but eg. small ARM boards that have 1GB or even less) a pretty good idea is to not use swap at all but better approaches that exist in the meantime. For example zram. In case you have a swap partition, uncomment it and ensure zram is being used. On all OMV3 images for ARM devices this is done by this simple instruction (pulling in an Ubuntu packet which doesn't matter since it's essentially just a simple startscript that sets up zram):

FILE=$(mktemp)
wget https://mirrors.kernel.org/ubuntu/pool/universe/z/zram-config/zram-config_0.5_all.deb -qO $FILE && dpkg -i $FILE

Starting with Debian Stretch / OMV4 there's a 'zram-config' package available which is then the preferred method.

We should keep in mind that 'stuff on the Internet' is mostly outdated. Swap recommendations date back to last century (copy&paste over and over again). It's 2018 and with all modern kernels we have way better options to deal with low-memory situations today than swap (fine a decade ago, questionable today on almost all devices).

People fearing anything that has been developed in this century: there's no need to put the swap partition on the drive the OS will be booted from. You can always get your system slow by letting the swap partition or file reside on a connected HDD (also great to prevent disk sleep)

Zitat von Blabla

If I don't have a swap partition I don't need to use the command "echo "vm.swappiness=0" >> /etc/sysctl.conf" right?

Exactly. No swap --> no swappiness. And with 8GB DRAM there's also no reason to activate zram.