My system has several hot swap SATA drives that I install or remove as I need them.  Previously, the first time I installed a new drive, I would use Diskdrake to add it to the fstab (with noauto set).  This way, my fstab had all the entries needed regardless of which drives were installed and I could simply use the "mount" command to mount them.  

Today, I discovered Diskdrake was removing the entries for the drives that were not present or were commented out.  Now, every time I swap out a drive, I have to rerun Diskdrake to rebuild the fstab.  I don't remember exactly when the last time I successfully added a drive this way, but I think it was in the past month.

There may be some value to removing entries for drives that are not present when Diskdrake is run to clean up fstab, but I think the default should be to only add entries as long as the UUID and mount point are unique.  Cleaning up should be an option.  It is much easier to manually remove an entry from fstab than it is to add an entry.

As a work around, I'll probably cycle through all my drives, have Diskdrake build the fstab entry, copy that entry to another file, and then copy all the entries into fstab.  

This does not seem to be a problem for network mounts in fstab, regardless of whether the target is up or not.

This seems similar to the problems reported in Bug 1041 and Bug 12033