updated readme

README.md

@@ -20,4 +20,23 @@ a daily snapshot at night (currently between 2am and 3am) and start the backup
 process later via cron (currently set to 4am).
 
 The documentation in our wiki can be found at:
-[https://wiki.cpi.imtek.uni-freiburg.de/CPIvServerDocumentation/ElabOnZfs]()
+https://wiki.cpi.imtek.uni-freiburg.de/CPIvServerDocumentation/ElabOnZfs
+
+
+## restoring backups ##
+
+1. copy a snapshot backup to the NAS
+    ```
+    cd /mnt/Datenspeicher/snap-backup-dataset/temporary-backups/
+    scp -i ../backup_key zfs_snap_backup@etha.cpi.imtek.uni-freiburg.de:~/zfs-backups/<backup-file> tmp-backup-file.gz
+    ```
+2. unzip the backup file and restore it into a dataset
+    ```
+    gunzip -c tmep-backup-file.gz | zfs receive -F Datenspeicher/test-backup
+    ```
+
+3. remove the (local) backup file
+    ```
+    rm tmp-backup-file.gz
+    ```
+