Imaging SCSI hard disks

From: Doc Shipley <doc_at_mdrconsult.com>
Date: Wed Sep 1 00:23:05 2004

Zane H. Healy wrote:

>>I've a couple of SCSI hard drives (DEC RZ24-S) that I'd like to do a
>>complete image of. If I stick them in a linux box and do a dd on them,
>>will it copy all the blocks from the device, or am I going to get
>
>
> Well, I can't really speak for the specific hardware you're going to use.
> However, I've taken 100MB and 200MB IBM drives out of my PDP-11/73,
> connected them to a Linux box via a SCSI controller, dd'd them off to a disk
> image. I've then ftp'd the disk image to a Mac, written the disk image to
> CD-R. Then taken the CD-R, placed it in the PDP-11/73's CD-ROM drive and
> booted the PDP-11 off of CD-ROM.
>
> 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.


        Doc
Received on Wed Sep 01 2004 - 00:23:05 BST