Imaging SCSI hard disks

[Zane H. Healy]

>>What I've not attempted to do is dd a disk image back to a SCSI HD.  It's on
>>my list of things to try, but who knows what decade I'll finally find the
>>time.
>
>   I haven't done this on a PDP-11, but have done it with SCO Unix, 
>Linux, and FreeBSD drives.  It's all geometry.  I do know that BSD 
>v2 sets partitions on cylinder boundaries, so the principles should 
>be the same as in later platforms.
>
>   You need a target disk with the same head/sector geometry as the 
>source.  The number of cylinders is a lot less critical, as long as 
>the target isn't smaller than the source.
>
>   You can actually get away with using an unmatched target as long 
>as fsck never runs.  :)
>
>   I dunno about other OS disks.  The little I know about RT-11's 
>filesystem implies that most any old disk should work.

My idea is actually to first dd the HD to a disk image, then prep 
that disk image under SIMH or E11.  Copy the data I want on the HD to 
the image using the emulator, and then dd it back to the HD. 
Logically it should work just fine.  With RT-11, you shouldn't even 
need to dd the HD to a disk image, just create whatever size disk 
image and dd it out there.  The other OS's would be a bit more picky. 
It should be a good way to get a large amount of data onto a PDP-11, 
however, I've yet to actually have a need to attempt it (I've just 
used Ethernet or CD-R to get data on).

		Zane

-- 
--
| Zane H. Healy                    | UNIX Systems Administrator |
| healyzh at aracnet.com (primary)    | OpenVMS Enthusiast         |
|                                  | Classic Computer Collector |
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