Migrating romm docker volumes guide

docs/Maintenance/Migrating-to-new-machine.md

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+
+## Migrating RomM to a new system
+
+Migrating RomM to a new system is possible, but all of the docker volumes must be copied for RomM to run correctly.
+
+Following the the setup in the [Quick Start Guide](https://docs.romm.app/latest/Getting-Started/Quick-Start-Guide/#build) these volumes are created be default
+
+RomM should be stopped before following this guide.
+
+```yaml
+volumes:
+    mysql_data:
+    romm_resources:
+    romm_redis_data:
+
+services:
+    romm:
+        volumes:
+            - romm_resources
+            - romm_redis_data
+    romm-db:
+        volumes:
+            - mysql_data
+```
+
+These volumes will need to manually moved to the new system. This is a straightforward process that includes determining their location and then copying them.
+
+### Determining the docker root directory and copying the volumes
+
+1. First determine the docker root directory
+
+```bash
+docker info | grep 'Docker Root Dir'
+```
+
+The expected output on a standard linux system:
+
+```bash
+Docker Root Dir: /var/lib/docker
+```
+
+2. Double check that the volumes have been created by docker and are owned by the docker engine
+
+```bash
+docker volume ls
+```
+
+Following the default quick start guide the following volumes will have been made
+
+```bash
+DRIVER    VOLUME NAME
+local     romm_mysql_data
+local     romm_romm_redis_data
+local     romm_romm_resources
+```
+
+3. Inspect each volume to get the exact location of the volume data
+
+```bash
+docker volume inspect romm_mysql_data | grep Mountpoint
+```
+
+- The output of the `docker inspect` will return the exact storage location of the volumes data
+
+```bash
+"Mountpoint": "/var/lib/docker/volumes/romm_mysql_data/_data",
+```
+
+4. Copy those volumes into a new location so that they can be safely migrated to a new system **each volume needs to be in its own folder**
+
+```bash
+cp -r /var/lib/docker/volumes/romm_mysql_data/_data/ /your/new/path/romm_mysql_data
+
+cp -r /var/lib/docker/volumes/romm_romm_redis_data/_data /your/new/path/romm_romm_redis_data
+
+cp -r /var/lib/docker/volumes/romm_romm_resources/_data /your/new/path/romm_romm_resources
+```
+
+5. Update the `docker-compose.yml` volume paths with the newly copied data to determine RomM still loads correctly.
+
+```yaml
+services:
+    romm:
+        volumes:
+            - /your/new/path/romm_romm_resources # romm_resources
+            - /your/new/path/romm_romm_redis_data # romm_redis_data
+    romm-db:
+        volumes:
+            - /your/new/path/romm_mysql_data # mysql_data
+```
+
+If RomM starts up correctly, then it is safe to copy all of your RomM folders to a new system.