How clone a bootable SCSI HD w/ OSR5?

I have an accounting system running on a bootable SCSI Hard Drive
ID=0 that is formatted under SCO OSR5. I have an identical SCSI drive
that is, as yet, unformatted, but connected as ID=1. How can I make
an exact copy of the primary drive on the secondary for use as off-site
disaster recovery media?
Also, how can I get a third identical SCSI drive to act as a "hot spare"
in case the primary drive fails? If I mount ID=0 and ID=1 drives in
separate removable carriers that allow the ID to be set from a
front bezel ID selector switch, could I remove ID=0 failed drive and
change ID=1 drive to ID=0 and reboot the system? Could I mount
the bootable hot spare to allow accounting data to be updated daily,
thereby creating a true on-line disaster recovery system? (Wouldn't
I have to change some default filesystem names to prevent duplicates
with the primary drive, e.g. boot, stand,etc., in order to mount?)
1. Need procedures to create off-site clone of boot drive.
2. Need procedures to create "hot spare" drive.
3. Need failover strategy if primary drive fails.

Note: every small server that does accounting should have a
          disaster recovery plan!
alanmcraeAsked:
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fredericoConnect With a Mentor Commented:
Do not try to make an exact copy.
Do a normal instalation, and configure the system exactly the same
way in both hard drives.

In order to make it easier and safe for you create a separated filesystem
to hold the "data" not related to the operating system. (the well known /u
filesystem).
ALWAYS use the same directory sctructure in both drives.

regardless of how you set up the filesystems, when working in the
"live" HD you can always mount the other HD partitions into a mount
point.

This means that if you have your files in /data in both machines, and you
need to copy from one HD to the other you need to mount the second
filesystem into a mount point.
eg
mount /dev/xxx /backuphd (where xxx is the device containing the partition you are mounting).

With this the filesystem names remain the same.

This will mean that you now have
/data
and
/backuphd/data
and so you can copy from /data/year1999 to /backuphd/data/year1999

If after the copy you need to boot from the second HD it will contain the
information required in the same places it was before.

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alanmcraeAuthor Commented:
Answer seems correct but does not explain why a bootable drive can't be cloned (copied in its entirety) to an identical drive), nor does it detail the command procedures necessary to copy non-OS file systems or device configuration files.
Note: MS-Windows 95/98/NT hard drives are easily cloned with utility software so that entire systems can be migrated onto larger hard drives or mirrored onto failover spares. Forcing users to recreate their OS platform all over again (OS, drivers, configurations, registration, etc.) to simply clone their systems is yet another reason why many companies are moving away from UNIX to Windows platforms.
Doesn't anyone out there have a better solution than re-installation?
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fredericoCommented:
Sorry, maybe I should have been more clear.
Option 1.

Step 1
In the normal HD add the second disk to the system. (mkdev hd).
This in only to add the necessary "/dev/xxx" files to the system. If you know how to create them by hand it may be better.

Step 2
Start the normal instalation on the spare HD.
Define the filesystems as you have in the online HD..
Once the filesystem are created abort instalation.
You now have the hd properly configured. (eventually, you will need to run dparam from the boot diskette to set up the boot sector properly, I do not remember. Read the manuals about this one.).

Step 3.
Now put both hd together as in step1.
Now supposing you have two filesystem
/
and
/u

We need to copy each one to the second HD.
So and following the same process described before
mount the root filesystem of the spare hd to /mnt
and do a copy from every root entry "/" in the first HD except
for "/u" (use cpio with the proper options).
After this to the same with the "/u" filesystem

This will hopefully do the trik.

Option 2. Dangerous and not guaranteed to work.

Step 1
In the normal HD add the second disk to the system. (mkdev hd).
This in only to add the necessary "/dev/xxx" files to the system. If you know how to create them by hand it may be better.

Now do a "dd if=/dev/xxx of=/dev/yyy bs=256k"

Where xxx is the raw device of the whole first HD and yyy of the second.

This may work also, although if you have bad sectors you may encounter some problems.

Try it and then comment it again.

Cheers
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alanmcraeAuthor Commented:
This does clarify the technical steps required to "clone" a bootable SCSI drive under SCO OpenServer.  As a small VAR who strongly advocates Disaster Recovery Planning, however, I am still interested in a faster, more automated method for "hard drive cloning" under SCO. Hey VARs and Developers, doesn't anybody have a shrink wrap solution to fast duplication of primary UNIX hard drives? Gotta keep moving to keep all these systems up-and-running!
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