Mount a backup /image

Mount a backup /image

Post by vn » Fri, 04 Jul 2003 01:45:53


Hi,

Is it possible to mount a saveset on a tape, saved with backup /image, like
a device ? Or is there any solution to recover a single file in a backup
/image without restore an entire disk?

Thanks

Victor

 
 
 

Mount a backup /image

Post by Bob Koehl » Fri, 04 Jul 2003 02:14:03



> Hi,

> Is it possible to mount a saveset on a tape, saved with backup /image, like
> a device ?

   No, unless you intend to write a lot of code.

Quote:> Or is there any solution to recover a single file in a backup
> /image without restore an entire disk?

   Yes.  You can recover any single file from any backup except
   /physical by using /select.  A save set created /image is fine with
   restore using /select and not /image.

   The only situation you need to worry about is the VAX Standalone
   BACKUP.  That software always does /image.  But it would be absurd
   to boot Standalone BACKUP to do a single file restore even if it
   could do it.  There's no problem using the online VMS BACKUP command
   to /select even if the /image was made using Standalone BACKUP.

 
 
 

Mount a backup /image

Post by Hoff Hoffm » Fri, 04 Jul 2003 03:23:09


:Is it possible to mount a saveset on a tape, saved with backup /image, like
:a device ?

  I would not want to try this approach.  (The contents of the saveset
  are not directly structured like a disk, so the work involved in
  translating the BACKUP checksums and structures back into a disk
  would be non-trivial.

  It is often expedient to keep disk-to-disk BACKUPs around for a while,
  while also rolling versions out to BACKUP savesets on archival media.
  And with spare disks around, reloading an image saveset back in is
  quite simple and quite fast -- and users can then self-select the
  files directly rather than having to provide the operator(s) with
  (sometimes incorrect :-) lists of requested files.

:Or is there any solution to recover a single file in a backup
:/image without restore an entire disk?

  Yes.  Please take the time to read through the BACKUP documentation in
  the system manager's essentials manual and the system management utilities
  manual, paying particular attention to the BACKUP command examples in the
  latter manual, and please also specifically see the documentation of the
  /SELECT qualifier.  (The existing documentation specifically points out
  how to select specific files from a BACKUP saveset.)

  MOUNT/FOREIGN mkcu:
  then
  BACKUP mkcu:saveset.bck/SAVE/SELECT=target-spec ddcu:[output-spec...]
  or
  BACKUP mkcu:saveset.bck/SAVE/SELECT=target-spec ddcu:[output-spec]
  or
  BACKUP...

  To use BACKUP correctly, you really need to know how to use the utility,
  and such knowledge is usually best acquired from the documentation.

  For pointers to the online documentation, please see the FAQ.  (See the
  sig for the FAQ URL.)

 ---------------------------- #include <rtfaq.h> -----------------------------
    For additional, please see the OpenVMS FAQ -- www.hp.com/go/openvms/faq
 --------------------------- pure personal opinion ---------------------------
        Hoff (Stephen) Hoffman   OpenVMS Engineering   hoff[at]hp.com

 
 
 

Mount a backup /image

Post by Rolon » Fri, 04 Jul 2003 06:58:14


Try $help backup/select
To mount a tape like a serial disk, the files need to be "copy"ed to it not
"backup"ed


Quote:> Hi,

> Is it possible to mount a saveset on a tape, saved with backup /image,
like
> a device ? Or is there any solution to recover a single file in a backup
> /image without restore an entire disk?

> Thanks

> Victor

 
 
 

Mount a backup /image

Post by vn » Fri, 04 Jul 2003 16:51:34


Yes it's a standalone backup of a VAX.
I made a confusion between the backup /image where /select qualifier isn't
allowed and a simple backup restore of this image saveset without the /image
qualifier where select is admitted.

It's definitely useless to spend time to mount a saveset like a device when
so simple ways exists.

Thank you




writes:
> > Hi,

> > Is it possible to mount a saveset on a tape, saved with backup /image,
like
> > a device ?

>    No, unless you intend to write a lot of code.

> > Or is there any solution to recover a single file in a backup
> > /image without restore an entire disk?

>    Yes.  You can recover any single file from any backup except
>    /physical by using /select.  A save set created /image is fine with
>    restore using /select and not /image.

>    The only situation you need to worry about is the VAX Standalone
>    BACKUP.  That software always does /image.  But it would be absurd
>    to boot Standalone BACKUP to do a single file restore even if it
>    could do it.  There's no problem using the online VMS BACKUP command
>    to /select even if the /image was made using Standalone BACKUP.

 
 
 

Mount a backup /image

Post by Everhar » Sat, 05 Jul 2003 05:47:10



> Try $help backup/select
> To mount a tape like a serial disk, the files need to be "copy"ed to it not
> "backup"ed



>>Hi,

>>Is it possible to mount a saveset on a tape, saved with backup /image,

> like

>>a device ? Or is there any solution to recover a single file in a backup
>>/image without restore an entire disk?

>>Thanks

>>Victor

You can access a backup/physical tape as if it were a disk, but not
backup/image.

On the sigtapes, or some of the freeware stuff look for a file called
CMPHIGHC.ZIP. This is billed as a compressing virtual disk, but the logic
is all there to let you create units of a driver called dtdriver there
(in memory of the good old TU56) and to run a host program called dthstimg
which can attach to dtdriver and to a magtape and the lot can present
a backup/physical tape (or just something like a dd dump to tape if you
are willing to specify the geometry by hand) as a readonly disk. It has
a lot of cache, and knows how to use CRC and XOR blocks to attempt
to recover from tape errors, and will pretend to allow writing to the
disk (but won't actually write to the tape) so even filesystems like
NTFS work with it.

This is usable if you like where you want to use back/phys (which can run
2-3 times faster than back/image on some machines) for backup yet still
get to files. It will only work if the whole image is on one tape though
(there being no simple way to tell a user which tape to mount if there are
more) and can take awhile to recover a badly fragmented file.

Glenn Everhart