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STACKER  NOTE                                                 STACKER NOTE
Subject:  "Lost Sector Groups" and Stacker
STAC FAX Index #3501 - 01/20/93                          
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Background

To be as efficient as possible, Stacker doesn't always completely erase   
previously  used  disk  areas  at  the  moment  when   an application  makes 
a file smaller. This happens most  often  when you run database applications, 
which tend to vary the file size a great  deal. As a result, the standard FAT 
entry shows that  data is  stored in  an area, while the Stacker drive's  
extended  FAT entry  shows  the  area was deleted  and  can  be  reused.  
This condition is completely harmless. In the normal course of events, you 
won't know it exists and  Stacker corrects it automatically.

However, if  you happen to run CHECK /=D /F, messages  reporting "lost sector 
groups" may appear. The lost sector groups similar to lost clusters that the 
DOS CHKDSK command can report, yet even less significant since  Stacker deals 
with them automatically.  Lost sector  groups  do  not  interfere  with  the  
operation  of  any programs,  not  even  Microsoft's Access, Borland's  
Paradox, or Lotus's Freelance. They do not corrupt any files or threaten  any
data.  Even though CHECK offers to delete these areas, you should respond 
with NO.

Result

Do not use the /=D switch with CHECK. This switch is intended for internal 
development purposes only. Lost sector groups are not a problem.

Running CHECK /F does not report or deal with lost sector  groups unless they 
take up more than 6% of the drive; in that case, it clears  the  condition. 
Running CHECK /=D /F reports all lost sector  groups and offers to delete the 
areas. Do not let  it  do this; respond NO if  CHECK offers to delete any 
area. If you want to  clear out lost sector groups for some reason, run 
SDEFRAG  or choose  Stacker  Optimizer from the Stacker Toolbox  (STAC).  
Any choice  (Full  Optimize, Quick Optimize, or  Restack)  completely clears 
lost sector groups.

















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Copyright 1993, Stac Electronics