Reinstalling a server without losing data

During a reinstallation, your server's storage is set up again from scratch. Everything on it is gone afterward. If you want to keep data, you must move it off the server beforehand.

There are two options for this, which serve different purposes. The Rettungsverzeichnis is additional temporary storage for your data that is kept during a reinstallation. The rescue system is an emergency operating system for cases where your server no longer boots.

The Rettungsverzeichnis

The Rettungsverzeichnis is an additional storage area that appears directly in your server. You move your data there, reinstall the server and then copy the data back. The storage area is kept during the reinstallation.

The advantage over downloading: the data stays in the data center. You need neither space on your own computer nor the time for two transfers over your internet connection.

1. Booking the directory

You book it in the customer portal under "Server" for the relevant contract. There, you select the size. The prices are shown next to it. The directory renews monthly until you cancel it. It can only be booked in addition to an existing server contract.

2. Making the directory available

What to do next depends on the type of your server:

• Container with OpenVZ: Restart your server once. After that, you find the directory under /mnt/rettung.
• Container with Incus: The directory is available immediately under /mnt/rettung.
• Virtual machine with KVM: The directory is attached to your server as an additional disk. Identify it with lsblk. The first time, create a file system (mkfs.ext4 /dev/vdX), then run: mkdir -p /mnt/rettung && mount /dev/vdX /mnt/rettung.

3. Moving the data

Copy what you want to keep. In our experience, this is your application data, the configuration and the databases:

rsync -a /var/www/ /mnt/rettung/www/

cp -a /etc/nginx /mnt/rettung/

Do not copy databases as files. Write a dump instead, because only then can it be imported reliably:

mysqldump --all-databases > /mnt/rettung/datenbanken.sql

Then use ls -la /mnt/rettung to check that everything has arrived, and compare the sizes with du -sh. Only then reinstall.

4. Reinstalling

Start the reinstallation in the customer portal. The Rettungsverzeichnis is kept and, for containers, is available again under /mnt/rettung after the first start of the new system. With KVM, mount the disk again after the reinstallation without formatting it.

5. Restoring the data and canceling the directory

Copy your data back and check that your applications are running. Then cancel the directory in the customer portal effective at the end of the month.

After a cancellation, we remind you by email on each of the three days before the end. After the end, the directory is disconnected from your server. The data is kept for another 14 days and can be reactivated. After that, it is deleted.

The rescue system

The rescue system, by contrast, is a small operating system that boots instead of your system. You need it when your server no longer boots, for example after a failed upgrade, with a damaged file system or if you have locked yourself out.

With KVM, you mount your storage there yourself. With containers, it is already mounted (Incus: /mnt). You can repair files, reset passwords or retrieve data. You start it in the customer portal for the relevant server. Afterward, you switch back to your own system there.

With KVM servers, you can combine both: if your server no longer boots, you can use a Rettungsverzeichnis in the rescue system to back up the data before you reinstall.

Important notes

• The Rettungsverzeichnis is not a backup. It is located in the same data center and is intended for the transition, not for permanent storage.
• Before the reinstallation, check that the data really is in the directory and not just in a folder of the same name on your server.
• Write down what you need to restore: application data, configuration, database dumps, certificates and cron jobs.

If you have questions, write to us at support@glowfish.de.