PSF/AIX: Why is /var/psf/queuename/dcl/mca larger than the /var/psf filesystem that contains it and how to copy?

ITEM: RTA000045418



QUESTION:                                                                       
Please explain what is happening. We have the psf working directory set         
to use /psf ( we have a symbolic link from /var/psf to /psf). Everything        
works fine. /psf was showing 6% full. The customer decided to                   
incorporate everything under /var and not have two temp spaces (/var and        
/psf). So we took out the link to /psf. Then we tried to copy /psf to           
/var/psf. What we found was that /var/psf was filling up before the             
recursive copy was completed. /var is 3 times the size of /psf. When we         
inspected further, we noticed that /psf was only using 6MB. Yet when we         
looked at some individual files within /psf, we found that they were            
bigger than the size of the filesystem which contained them.                    
Specifically, /psf (also known as /var/psf due to the link) contained           
6MB of data according to the df command. However,                               
/var/psf/queuename/dcl/mba showed that it was 8MB with the ls command          
and /var/psf/queuename/dcl/mcb showed that it was 10MB with the ls              
command (as best I can recall). This would explain why when I dropped           
the link and tried to copy the files to the /var/psf under the /var             
filesystem that the filesystem would fill up. Can you explain why the           
mca and mcb files were showing larger than the filesystem said they were        
and how we can consolidate back to /var for both the /var/psf working           
directory and the /var/spool/qdaemon and /var/spool/lpd queueing                
directories. Thanks so much.                                                    
                                                                                
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A:                                                                              
The files under the /var/psf/printername/dcl directory are memory mapped.       
As such, they are defined to be, say 6Meg, but they are sparse and only a       
small amount of data is actually contained therein. Thus, DASD is not          
wasted. If you use cp to copy any of these memory mapped files, the             
target file will be all on disk since cp does not have the intelligence         
to maintain the memory mapping setup.  This explains your experience.           
                                                                                
Now, what to do about it.                                                       
                                                                                
It sounds like you know how to undefine the symbolic links and get the          
file systems back in order.  That is good news.  The additional piece           
that you need to know is:                                                       
                                                                                
  1.  Bring down all instances of PSF (using psfctl -dt) before                 
      doing anything.                                                           
                                                                                
  2.  Delete (yes, really erase) all of the files under each of the            
      /var/psf/printername/dcl directories.  When PSF for that queue            
      is started up again, they will be recreated and all will be well.         
                                                                                
      Example:  cd /var/psf/printer1/dcl                                        
                del *                                                           
                mca mcb scb                                                     
                del: Remove these files? Enter y or the ENTER key for           
                  yes.                                                          
                y                                                               
                                                                                
  3.  Copy all of the directories/files as was started before.                  
      This time, there will be enough room because the dcl                      
      files are out of the picture.                                             
                                                                               
I hope this helps resolve the problem.  If not, please reopen this              
item.                                                                           
                                                                                
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This item was created from library item Q666036      CTLKN                      
                                                                                
S e a r c h - k e y w o r d s:                                                  
psf/6000 psf/aix dcl filesystem mca mcb psf aix /var /var/psf                   
                                                                                
                                                                                
                                                                                
                                                                               


WWQA: ITEM: RTA000045418 ITEM: RTA000045418
Dated: 10/1998 Category: PSF6000
This HTML file was generated 99/06/24~12:43:18
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