Resized Azure VM based on the Linux Docker+Rethinkdb image and the data was lost, is this to be expected?

Question

Had about 20 documents in one Rethinkdb Database [Docker-based] on a Standard A1 and wasn't using it much so I decided to downsize it to Standard A0, after a few minutes the Rethinkdb server came back online completely empty (with only the test db)

The data was purely for test so no issue there, but is it expected to if someone upgrades a Linux + Docker + [container, Rethinkdb in this case] to lose data? Are there any steps to prevent that?

Answer 1

Linux systems on Azure have a local disk that is mounted as /mnt anything stored on this drive will be erased upon reboot. You can use this disk for caching and where temporary processing is required, but you should avoid storing anything that might be needed.

The best solution is to mount a data disk to the machine and use that as a volume to store data on.

This is also true of the D: drive on Azure Windows VMs