I just found out by accident that recover & _recover are not the same command, or at least _recover can not fix problems that recover can.
I have a 200i drawing that was migrated to 2004. It is approximately 15 Megs in size, covering 2.2 Miles of creek channel, and spoil site locations. I have almost 50 tabs and 100 viewports in the drawing. The layout regen option is set to cache model and last layout (to minimize cache usage)
I noticed that while plotting with Batch plot that the cache size kept increasing, to the point I had cross section layouts that were using 1.5 Gigs. This caching problem would continue until a fatal error would occur. After the error I tried to open the drawing and received another fatal error, so I tried filedrawing utilities_recover and received another fatal error.
After trying to recover the drawing several times I went to an earlier version of the plan. opened the drawing and then saved the drawing, exited out of AutoCAD and reopened AutoCAD, and did a cancel instead of opening a drawing. I then tried to do a recovery on the drawing I just saved and received the same fatal error as the new version of the drawing. I opened and saved the older version under a different name, and then tried to filedrawing utilities_recover the original drawing, same results. I then typed recover on the command line and the drawing opened. I then typed recover again and tried recovering the newest version of the drawing and it worked. I then tried the filedrawing utilities_recover and received the old fatal error. The drawing still has the cache usage problem so I have split up the batch file and hope this will allow me to finish the function in phases.
This leads me to believe the filedrawing utilities_recover is a soft version of recover.