[Info-vax] image backup on itanium

[Stephen Hoffman]

On 2015-05-02 21:25:26 +0000, Stephen Hoffman said:

> On 2015-05-02 20:58:10 +0000, Hans Vlems said:
> 
>> an image backup also keeps track of linked directories, it knows about 
>> set file/enter.
>> AFAIK copy is unaware of that and would produce a much larger footprint 
>> than backup does.
> 
> Neither COPY nor BACKUP /NOIMAGE is appropriate for and neither will 
> work particularly well for system disks on any of the three 
> architectures.  Not without additional assistance after restoration, 
> and prior to attempting a bootstrap.  You'll end up with replicated 
> files and missing linkages, and probably also with some degree of 
> creeping system management confusion ensuing.

ps: for creating disk images, COPY won't directly work for DVD to 
magnetic disk transfers, as the boot offsets differ due to the 
differing block sizes — you'll get a copy of an El Torito disk image 
created on a magnetic disk, so you'll end up with 2048-byte sector 
offsets and not the necessary 512-byte sector offsets.  SET BOOTBLOCK 
will fix this case for COPY, and BACKUP /IMAGE will try to pick the 
appropriate sector size based on the target disk.  That all works 
correctly except if you plan to burn the disk to DVD, when you'll need 
to override that with a specific SET BOOTBLOCK //BLOCK_SIZE command.  
This stuff is all covered in the article I've linked to.



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