Re: Deleting alias files (blocks deleted)

"Bill Todd" <billtodd@xxxxxxxxxxxxx> wrote in message
news:z6GdnYbeu59n6DHeRVn-oA@xxxxxxxxxxxxxxxxxxxxxxxxxxx
>Soft ('symbolic') links often can (in systems that support them) satisfy
>these requirements without raising the interesting issues that hard links
>do, but IIRC hard links were invented first (and indeed the interesting
>issues therein later caused soft links to be added to Unix - does VMS have
>anything like them?).

There are three 'options' in this area.

VMS supports the traditional aliases, which people have being discussing.

UNIX style symbolic links, (also with support for NFS), which are very new
to VMS, it's certainly available in field test for V8.2 / V8.2-1, but don't
think it has been properly released yet. ODS5 only.

Finally ODS5 supports hard links as well.

>From the VMS docs...

"Both ODS-2 and ODS-5 support aliases, which are additional names for a file
or directory. Only ODS-5
supports hard links. One of the main differences with hard links enabled is
the way the DCL DELETE
command works. With hard links enabled, if you issue the DELETE command to
delete a file that has
one or more aliases associated with it, the command only deletes the alias
by which the file is being
accessed. The actual file continues to exist and is accessible by any
remaining alias. The file is deleted
only when the last remaining alias is deleted. Without hard links enabled,
the DELETE command
deletes both the alias by which the file is being accessed and the file
itself. Any other aliases remain but
the file is no longer accessible because it is no longer present. Thus, the
remaining aliases are unusable.

If enabling hard links has any drawbacks, they are minor and probably of
concern only in rare
circumstances. For example, if disk quotas are in effect, though owners of a
file can delete any links to a
file in a directory they can access, hard links in other users' directories
might cause a file to be retained,
and the file size continues to be charged against that owner's disk quota.
In general, be aware that enabling hard links does change the file system's
behavior and that applications
and management practices should respond accordingly (instead of being
alias-specific, for example)."

Alex


.

Relevant Pages

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