[comp.sys.mac.system] Backing up aliases

davidl@iSC.intel.com (David Levine) (06/12/91)

Is it possible to back up and restore a disk containing aliases using a 
backup program that was not written with System 7 in mind?

If not, which backup programs are currently capable of backing up aliases?

If so, how on Earth is that possible?

- David D. Levine, Intel Supercomputer Systems Division
  davidl@ssd.intel.com  - or -  davidl@isc.intel.com
  "The best way to predict the future is to invent it."

oleary@ux.acs.umn.edu (Doc O'Leary) (06/13/91)

In article <1402@ssdintel.isc.intel.com> davidl@iSC.intel.com (David Levine) writes:

>Is it possible to back up and restore a disk containing aliases using a 
>backup program that was not written with System 7 in mind?
>
>If not, which backup programs are currently capable of backing up aliases?
>
>If so, how on Earth is that possible?

My version of Redux by Microseeds Publishing (1.63) is pre-System 7 (dated
October 9, 1990) and it has no problem with backing up aliases.  It, I
believe, treats them like generic documents (probably like < 7.0 systems
treats them).  Once restored, System 7 recognizes them as aliases again.

In fact, I'd be wary of backup programs that COULDN'T handle aliases.  I'm
not one to trust important data to badly written programs . . .

         ---------   Doc


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dorner@pequod.cso.uiuc.edu (Steve Dorner) (06/13/91)

In article <4114@ux.acs.umn.edu> oleary@ux.acs.umn.edu (Doc O'Leary) writes:
>In fact, I'd be wary of backup programs that COULDN'T handle aliases.

My first reaction was similar; an alias is a file, so any backup program
should handle it.  Then I had an awful thought.

Suppose you do a full backup and restore.  Won't fileid's and dirid's have
changed so as to make the aliases useless?  After all, a backup program
can only restore file and directory names, not id's.
--
Steve Dorner, U of Illinois Computing Services Office
Internet: s-dorner@uiuc.edu  UUCP: uunet!uiucuxc!uiuc.edu!s-dorner

russotto@eng.umd.edu (Matthew T. Russotto) (06/14/91)

In article <1991Jun13.142519.20475@ux1.cso.uiuc.edu> dorner@pequod.cso.uiuc.edu (Steve Dorner) writes:
>In article <4114@ux.acs.umn.edu> oleary@ux.acs.umn.edu (Doc O'Leary) writes:
>>In fact, I'd be wary of backup programs that COULDN'T handle aliases.
>
>My first reaction was similar; an alias is a file, so any backup program
>should handle it.  Then I had an awful thought.
>
>Suppose you do a full backup and restore.  Won't fileid's and dirid's have
>changed so as to make the aliases useless?  After all, a backup program
>can only restore file and directory names, not id's.

Sure, but the aliases store lots of ways of finding the file.  I would be
really surprised if full pathname wasn't one of them.

--
Matthew T. Russotto	russotto@eng.umd.edu	russotto@wam.umd.edu
     .sig under construction, like the rest of this campus.

jas@ISI.EDU (Jeff Sullivan) (06/14/91)

In article <4114@ux.acs.umn.edu> oleary@ux.acs.umn.edu (Doc O'Leary) writes:

>In article <1402@ssdintel.isc.intel.com> davidl@iSC.intel.com (David Levine) writes:
>
>>Is it possible to back up and restore a disk containing aliases using a 
>>backup program that was not written with System 7 in mind?
>>
>>If not, which backup programs are currently capable of backing up aliases?
>>
>>If so, how on Earth is that possible?
>

Retrospect 1.3 backs up aliases.

jas
--
--------------------------------------------------------------------------
Jeffrey A. Sullivan		| Senior Systems Programmer
jas@venera.isi.edu		| Information Sciences Institute
jas@isi.edu                    	| University of Southern California

oleary@ux.acs.umn.edu (Doc O'Leary) (06/14/91)

In article <1991Jun13.142519.20475@ux1.cso.uiuc.edu> dorner@pequod.cso.uiuc.edu (Steve Dorner) writes:
>In article <4114@ux.acs.umn.edu> oleary@ux.acs.umn.edu (Doc O'Leary) writes:
>>In fact, I'd be wary of backup programs that COULDN'T handle aliases.
>
>My first reaction was similar; an alias is a file, so any backup program
>should handle it.  Then I had an awful thought.
>
>Suppose you do a full backup and restore.  Won't fileid's and dirid's have
>changed so as to make the aliases useless?  After all, a backup program
>can only restore file and directory names, not id's.

I don't know about other backup programs, but Redux backs up *everything*
(or at least it seems).  It backs up the window sizes, the location of the
files and folders with the window, the window locations on the screen, etc.
I've never checked, but I'd bet that the id's are saved as well.  When I did
complete restore back when I was using 7.0b4 (after moving from a 40MB to a
105MB internal) everything was EXACTLY as I left it, and the aliases had no
problem opening the original.

Oh, BTW, I have no connection with Microseed Publishing except as a person
who has sent in their registration card and hasn't seen need to bug them
since.

         ---------   Doc


**********************   Signature Block : Version 2.6  *********************
*                                     |                                     *
* "Was it love, or was it the idea    |   It's hard to look cool with your  *
*  of being in love?" -- PF           |   arm Super-Glued to your forehead  *
*    (BTW, which one *is* Pink?)      |                                     *
*                                     |   --->oleary@ux.acs.umn.edu<---     *
******************   Copyright (c) 1991 by Doc O'Leary   ********************

potts@us.cc.umich.edu (Paul Potts) (06/14/91)

In article <4122@ux.acs.umn.edu> oleary@ux.acs.umn.edu (Doc O'Leary) writes:

>
>I don't know about other backup programs, but Redux backs up *everything*
>(or at least it seems).  It backs up the window sizes, the location of the
>files and folders with the window, the window locations on the screen, etc.
>I've never checked, but I'd bet that the id's are saved as well.  When I did
>complete restore back when I was using 7.0b4 (after moving from a 40MB to a
>105MB internal) everything was EXACTLY as I left it, and the aliases had no
>problem opening the original.
>
Redux is very good, IMO.  I own it as well.  I was very impressed to find
that it ran under system 7 with no problems whatsoever.
I have tried all the other major backup utilities out there (at least, the
ones that were available two years ago) and Redux is the only one that never
gave me any trouble.  Diskfit was 2nd, and Fastback was the worst.

People don't need to worry about their backup program keeping the
exact file refnums for aliases to continue to work.  According to IM-6,

"Even if a file has been renamed or moved on a volume, the Alias manager
can find it quickly through its file ID. 

If the search by file ID or directory ID fails, fast search looks for the
target by name in the original parent directory.  This search locates the
target if its file or directory ID has changed but it still by the same name
in the parent directory (for example, if the target was restored from backup).
...
If the search by file ID or directory ID fails and if fast search cannot find
the original parent directory, it searches for the target by full pathname.
This search finds the target if it resides in the same location on the
volume but the directory ID of its parent directory has changed (for example,
if the entire parent was restored from backup).

If the search by full pathname fails, fast search attempts to find the
file by tracing partial pathnames up through all parent directories...
etc..."

(I-M 6, p. 22-7)

ResolveAlias will then update the alias record, so presumably if the file
was hard to find, it will be easy to find next time the alias is used.

People don't give Apple enough credit.  Y'all didn't seriously think a minor 
obstacle like changing the file refnum would stop the alias manager from
finding it, did y'all?

(you can run, but you can't hide...)
-Paul Potts-
potts@itl.itd.umich.edu