[Info-vax] Request description of UFS for VMS person

[Bill Gunshannon]

In article <176uZD2KcidF-pn2-EGCxjRCvkpZd at rikki.tavi.co.uk>,
	"Bob Eager" <rde42 at spamcop.net> writes:
> On Wed, 22 Apr 2009 11:51:40 UTC, billg999 at cs.uofs.edu (Bill Gunshannon)
> wrote:
> 
>> In article <gsms0d$dn$3 at naig.caltech.edu>,
>> 	glen herrmannsfeldt <gah at ugcs.caltech.edu> writes:
>> > Bill Gunshannon <billg999 at cs.uofs.edu> wrote:
>> > (snip)
>> >  
>> >> Are you saying that the blocks used by a file that has been deleted are
>> >> not going to be reused?  Assuming a decent file allocation scheme I would
>> >> expect the freed blocks to be in locations that were likely to be considered
>> >> prime real estate for the next file that needed space.
>> > 
>> > The MS_DOS allocation method seems to be such that the most
>> > recently allocated blocks are the last to be reused, assuming
>> > no reboot in the mean time.  As well as I understand it, there
>> > is a pointer to the last allocated blocks that is incremented
>> > until it gets to the end, and then starts over from the beginning.
>> 
>> And why does an alocation scheme as bad as this not surprise me?
>> No wonder we spent so much time de-fraging MSDOS.  :-)
> 
> It's there to make undelete useful. And that was only on MS-DOS, where 
> disks were reasonably small.

Considering that MS never provided an UNDELETE command I doubt that was
the reason for the allocation scheme they used.  More likely their
programmers just didn't know any better.

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>