Given the recent news regarding CentOS, I am migrating all of our Linode servers from CentOS to Ubuntu, starting with our staging server that runs Virtualmin Professional. I've successfully set up a new Ubuntu 20.04.1 LTS Linode and installed Virtualmin using the install script downloaded from the Software Licenses page in my account. Then, I did a full backup of the old CentOS server using the ZIP file format (one file per server, new format) and the new Ubuntu server as the SSH destination for the backup.
Everything worked properly, the backup took about an hour and ten minutes and resulted in about 28 GB worth of files. However, restoring that backup on the Ubuntu machine resulted in something extremely odd.
I started the restore at around 10 PM EST last night (Sunday, January 3) and it seemed to hang on the "Extracting backup archive files" step. I checked it around 1:30 AM this morning (Monday, January 4) and it was still on that step. Finally, when I checked it again around 6 AM the restore process had completed. But what I'm wondering is, why would it take at least 4 hours (if not potentially longer) to restore a 28 GB backup of about 184 virtual servers that only took an hour to actually back up?
I have done restores of backups of similar sizes and contents on other servers (running CentOS though instead of Ubuntu) and they usually complete quite quickly. This is the CLI command I ran to do the restore: virtualmin restore-domain --source /vm/ --all-domains --all-features --all-virtualmin
Something that might help - I inspected the size of /tmp every time I checked the restoration process. A few minutes after I started the restore last night, when I first checked and found it stuck on the extracting step, the /tmp folder was less than 1 GB in size. When I checked it again around 1 AM and it was still extracting archives, the /tmp folder was still less than 1 GB in size and had barely increased.
The restore was successful according to Virtualmin but some things are still broken (i.e Nginx throws 'no path in the unix domain socket in upstream "unix:"'), so I may have to try the restore again but wanted to see if there's any way it could be sped up first LOL. This is a fresh Ubuntu 20.04.1 LTS system with 8 GB RAM and 160 GB SSD storage so I'm not quite sure what could be going on, but I am very grateful in advance for any assistance provided!