[Info-vax] backup /image on Windows or Unix?

[Bill Gunshannon]

In article <kdp1jo$r2b$1 at news.albasani.net>,
	Jan-Erik Soderholm <jan-erik.soderholm at telia.com> writes:
> Bill Gunshannon wrote 2013-01-23 16:51:
> 
>>> How is that "n.n % fragmentation calculated ?
>>
>> Don't know if I ma qualified to answer that.
> 
> Well, it was not *I* that used the procentages to try to prove
> something, was it? *I* have nothing to prove here.

Neither do I.  I was offering simple help to a question someone posted.
As always, people are free to accept or reject anything they read on
USENET.

> 
> 
>> ...why there have never been any third-part defrag programs for Unix
>> (at least none I have ever seen),
> 
> Then you haven't looked. Even Digital UNIX had one.
> HP-UX and Linux has defrag tools.

Well, I guess it would depend on the file system being used.  UFS,
the current (and for quite some time now) statndard Unix file
system takes care of most fragmentation on the fly.  HPUX ships
this file system but calls it HFS.  It also provides other files
systems.  They may (and probably do) handle fragmentation in a
different manner.  the default filesystem in Linux is not UFS.

I just looked at the supposed "Best Disk Defragmenter Software"
packages for 2013.  They are all Windows.  Went to the Wiki for
a "List of defragmentation software" only one of them is for a
Unix system and that is for Apple's HFS (not to be confused with
the HFS that is actually UFS.)  Everything else is for variants
of Windows.

A little more research finds an explanation from The University of
Washington in Seattle that supports what I said above.  It also
explains that Digital Unix did not use UFS but had something
called ADVFS which did suffer from fragmentation.  Linux has
a defrag program for their EXT2 file system.

So, I guess it comes down to what filesystem (and probably what
Unix) you are using.  For the most part, defraging is seldom
needed in Unix.

Don't take my word for it, google will provide lots of pointers
to other people saying the same thing, some with decent explanations.

bill


-- 
Bill Gunshannon          |  de-moc-ra-cy (di mok' ra see) n.  Three wolves
billg999 at cs.scranton.edu |  and a sheep voting on what's for dinner.
University of Scranton   |
Scranton, Pennsylvania   |         #include <std.disclaimer.h>