Does the file system need reorganization under HP-UX?

[Paul Hite]

In article <5526 at uafhp.uark.edu>, tn03 at uafhcx.uucp (Tn3270 access) writes:
> 
> I have been asked to design a program to reorganize the file system under HP-UX
> because there is concern that performance may suffer if data gets too far
> scattered across the disk?  Is this true.  
> 


HP-UX (in it's current incarnation on the 300's and 800's) uses a modified
version of the Berkeley file system.  In theory the cylinder group stuff tends
to keep the data localized and thus periodic re-orgs are not needed.  If a 
file system is allowed to become too full, the last files written can be 
scattered.  There is a min-free parameter set to 10%.  If this is respected,
the file system can't become too full.  Anyway that what I have read and we 
have never re-orged our file systems.

If re-orging a file system was necessary, I probably wouldn't trust a 
program that attempted this "in place".  Rather I would just dump the files
to tape, rebuild the file system, and restore the files.  If I did use an
"in-place" type program, I would still want a backup.  So the re-org 
program would have to be faster than reloading the files to be a win.

A program to reorg a file system is a job for a real guru.  I doubt that
either of us has any business attempting such a feat.  But if you do pursue
this, you may want to post any further questions to comp.sys.hp.  That's 
where the HP-UX gurus hang out.

Paul Hite   PRC Realty Systems  McLean,Va   uunet!prcrs!paul    (703) 556-2243
        You can't tell which way the train went by studying its tracks.