Imaging SCSI hard disks

[Doc Shipley]

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