+\label{ConcurrentDiskJobs}
+\section{Concurrent Disk Jobs}
+\index[general]{Concurrent Disk Jobs}
+Above, we discussed how you could have a single device named {\bf
+FileBackup} that writes to volumes in {\bf /home/bacula/backups}.
+You can, in fact, run multiple concurrent jobs using the
+Storage definition given with this example, and all the jobs will
+simultaneously write into the Volume that is being written.
+
+Now suppose you want to use multiple Pools, which means multiple
+Volumes, or suppose you want each client to have its own Volume
+and perhaps its own directory such as {\bf /home/bacula/client1}
+and {\bf /home/bacula/client2} ... With the single Storage and Device
+definition above, neither of these two is possible. Why? Because
+Bacula disk storage follows the same rules as tape devices. Only
+one Volume can be mounted on any Device at any time. If you want
+to simultaneously write multiple Volumes, you will need multiple
+Device resources in your bacula-sd.conf file, and thus multiple
+Storage resources in your bacula-dir.conf.
+
+OK, so now you should understand that you need multiple Device definitions
+in the case of different directories or different Pools, but you also
+need to know that the catalog data that Bacula keeps contains only
+the Media Type and not the specific storage device. This permits a tape
+for example to be re-read on any compatible tape drive. The compatibility
+being determined by the Media Type. The same applies to disk storage.
+Since a volume that is written by a Device in say directory {\bf
+/home/bacula/backups} cannot be read by a Device with an Archive Device
+definition of {\bf /home/bacula/client1}, you will not be able to
+restore all your files if you give both those devices
+{\bf Media Type = File}. During the restore, Bacula will simply choose
+the first available device, which may not be the correct one. If this
+is confusing, just remember that the Directory has only the Media Type
+and the Volume name. It does not know the {\bf Archive Device} (or the
+full path) that is specified in the Storage daemon. Thus you must
+explicitly tie your Volumes to the correct Device by using the Media Type.
+
+The example shown below shows a case where there are two clients, each
+using its own Pool and storing their Volumes in different directories.
+
+