[Info-vax] BACKUP/IMAGE/EXCLUDE...?

[JF Mezei]

Out of curiosity, when one does BACKUP/IMAGE, backup does backup the
boot block on the disk and is able to set it properly on the target disk.

Does anyone know how this is actually done ?

Does the boot block contain information about the file-id as well as its
physical location on the disk ?

Or does Backup lookup the block number pointed by the boot block and
scans indexf.sys to find which file begins at that block so it can know
its file ID ?

I take it that Backup then merely flags the file as being the boot block
so that in a restore operation, once Backup has written the file, it
will be reminded to set the boot block to that files new location on the
disk ?


What about the EFI partition ?  Does the save set header information
contain some information about the EFI partition so that backup knows
NOT to use any of the blocks that will be needed so that by the time it
gets to creating the ODS5 EFI partition file that needs to be allocated
on those blocks, those blocks will still be available ?

Does VMS support variable size EFI partition files, or is a specific
file size hardcoded in the file system/backup making it easier when
initialising a disk to already pre-allocate the blocks needed to store
the EFI partition ?