After a few hours, I’m not sure how to entitle this post, so I’m quoting all the suspects.

I am migrating a dedicated server running Debian 12 with LXC, nginx as a reverse proxy, and a couple of containers. I use rsync with -avhze options.

MariaDB inside one of the containers doesn’t start, and it seems that the permissions on some files have changed through rsync.

Details :

What I did so far, in broad outline :

• Install Debian 12 and packages I need on the new server (nginx, LXC, …)
• rsync -avhze /etc/[someSelectedFolders] and other config folders / files (not all /etc but only those relative to packages of the same version)
• rsync -avhze /var/lib/lxc on the new server
• Start a first container that serves a dokuwiki site : all is fine (after managing certificate et DNS of course)
• Start a 2nd container serving a Nextcloud instance : that’s where the trouble starts… despite I already did a migration a few years ago, with the same process, without problems…

The LXC container starts, but inside it, MariaDB doesn’t start (code=exited, status=1/FAILURE).

From the container, /var/log/mysql/error.log says :

2024-07-10 18:04:08 0 [Note] Starting MariaDB 11.4.2-MariaDB-deb12 source revision 3fca5ed772fb75e3e57c507edef2985f8eba5b12 as process 197
2024-07-10 18:04:08 0 [Note] Using unique option prefix 'myisam-recover' is error-prone and can break in the future. Please use the full name 'myisam-recover-options' instead.
2024-07-10 18:04:08 0 [ERROR] InnoDB: The data file './ibdata1' must be writable
2024-07-10 18:04:08 0 [ERROR] InnoDB: The data file './ibdata1' must be writable
2024-07-10 18:04:08 0 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
2024-07-10 18:04:08 0 [Note] Plugin 'FEEDBACK' is disabled.
2024-07-10 18:04:08 0 [Note] Plugin 'wsrep-provider' is disabled.
2024-07-10 18:04:08 0 [Note] Zerofilling moved table:  './mysql/plugin'
2024-07-10 18:04:08 0 [ERROR] Unknown/unsupported storage engine: InnoDB
2024-07-10 18:04:08 0 [ERROR] Aborting

After an nth check of the permissions on /var/lib/mysql/, I noticed that the owner and group has changed through rsync -avhze ... :

Old server :

root@mycontainer:/# ls /var/lib/mysql/
...
-rw-rw----  1 mysql mysql 290M 10 juil. 18:10 ibdata1
...

New server :

root@mycontainer:/# ls /var/lib/mysql/
...
-rw-rw----  1   996 polkitd 290M Jul 10 17:58 ibdata1
...

Despite the -a option, which preserves owner, groups and permissions.

I checked with less /etc/passwd that the users are identical in both copies of the container.

So my questions are :

• How is it possible ? And who’s fault is that ? (rsync, mariadb less likely, other ?)
• What is the good way to solve this ?
• Which other files may be affected ? How could I check this “container-widely” if necessary ?

Thanks in advance for any tip!