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Add SWAP to Linux VM’s on Azure


Every virtual machine (VM) on Azure has what we call a temporary (ephemeral) disk which is recommended to be used ONLY as temporary storage and that includes SWAP files or data that does not need to be available upon a reboot or saved , the data stored in this drive will be lost.
To create a swap file in the directory that's defined by the ResourceDisk.MountPoint parameter, you can update the /etc/waagent.conf file by setting the following three parameters:

ResourceDisk.Format=y
ResourceDisk.EnableSwap=y
ResourceDisk.SwapSizeMB=xx

Note The xx placeholder represents the desired number of megabytes (MB) for the swap file.
Where the size is in MB, so for instance, to create a SWAP file of 4GB you could use these lines:

ResourceDisk.Format=y
ResourceDisk.EnableSwap=y
ResourceDisk.SwapSizeMB=4096


Restart the WALinuxAgent service by running one of the following commands, depending on the system in question:

Ubuntu: service walinuxagent restart
Red Hat/Centos: service waagent restart
Run one of the following commands to show the new swap apace that's being used after the restart:

dmesg | grep swap
swapon -s
cat /proc/swaps
file /mnt/resource/swapfile
free| grep -i swap