[Info-vax] Problems restoring image-backup

[Stephen Hoffman]

On 2016-06-28 16:25:59 +0000, Michael Moroney said:

> Does a BACKUP/IMAGE restore create GPT.SYS on the destination volume 
> when  done on an Itanium?  ($ HELP BACKUP /GPT suggests no)
> An Alpha boot loader wouldn't know what to do with GPT.SYS.
> Look to see if [000000]GPT.SYS exists on the supposedly bootable volume.

In no particular order...

BACKUP calls the setboot API to process the target volume on behalf of 
BACKUP.   BACKUP doesn't deal with boot blocks, setboot does.

The intent here was to correctly process disks with or without the 
special-cased GPT.SYS file.

Itanium servers can boot from non-GPT disks (MBR-only) though AFAIK 
that wasn't something officially supported by OpenVMS development.

A disk without a GPT should be restored correctly, but — if you're 
restoring a saveset that doesn't contain one, a GPT.SYS file will not 
be created for you.

The removal of the requirement for the primary home block is secondary 
to some GPT-related disk shuffling; the primary home block and the GPT 
overlap.

The /GPT stuff was a way to shut off the creation and population of the 
GPT on restoration.

The restoration of a saveset containing a GPT.SYS file requires BACKUP 
to regenerate the contents of that file; BACKUP can't copy the contents 
from the saveset to the target.


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