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

[johnwallace4 at yahoo.co.uk]

On Apr 21, 9:42 pm, JF Mezei <jfmezei.spam... at vaxination.ca> wrote:
> Bob Eager wrote:
> > As you say, unlink just removes a directory entry; all directory entries
> > are 'equal', so when the last one goes, the use count in the inode drops
> > to zero. At that point, the inode is cleared and the file blocks
> > returned to free space.
>
> > On MS-DOS, the first byte of the directory entry was set to a special
> > 'deleted' value, and file blocks were marked as free. Basic, but
> > sufficient.
>
> Does this mean that "undelete" is not possible on Unix file systems
> because its logical equivalent to the entry in indexf is actually wiped
> out ?
>
> With VMS and DOS, it was possible to undelete files because entries were
> just flagged as available and remained until used by another file.

DEC's AdvFS had (has?) undelete (though you didn't get the actual
Undelete tool without the separately licenced AdvFS Tools, iirc). But
lots of other Unix filesystems don't. All filesystems are not created
equal.