SUMMARY Creating New Disk Image

From: Matt Mc Namara <mmcnamar_at_gr-lakes.com>
Date: Wed, 12 Mar 1997 11:51:46 -0500 (EST)

Here is a summary of the responses that I got. All are very useful, I used
the dd, being it was a utility that i've used many times in the past. The
only thing I found, was that I needed to do a disklabel -z /dev/rrz5c before
I started the dd.

Thank you to all!

Alan Rollow writes...

The probably failed because the disk drivers make the label
read-only. Since it is the first sector of the disk, it
fail immediately. If you're going to copy with dd(1) do
it before you label the disk. The disadvantage of using
dd(1) is that it copies every sector, whether it is used
by the file systems or not. It also copies the page/swap
space, which doesn't anything useful on it for a copy.

Still, if you use a good block size for the copy and the
file systems are full enough, dd(1) can be faster than
backing up each individual file system. Not using a
block size will default to one sector, which will make
dd(1) horribly slow. Using a bad block size means you
miss data at the end of the disk. Use a reasonably large
factor of the capacity. Don't use track or cylinder
sizes, unless you *know* these are a multiple of the
capacity.

To copy the file systems you:

1. Create the corresponding file system on the new device:

        # newfs /dev/rrz5a

    or:

        # mkfdmn /dev/rz5a new_root
        # mkfset new_root root

2. Mount it:

        # mount /dev/rz5a /mnt

    or:

        # mount -t advfs new_root#root /mnt

3. Copy the data using dump/restore of vdump/vrestore:

        # dump 0f - / | ( cd /mnt ; restore rf - )

    On V4.0 you need the dump patches that fix dumping to a
    pipe.

4. Unmount the file system and repeat for the next one. If
    your file systems are AdvFS, check the documentation to
    if they suggest an alternate procedure for backing up
    the file systems.

Ruben Azzopardi writes...

eg for the /usr filesystme
mount /dev/rz5g /mnt
vdump -0 -f - /usr | (cd /mnt; vrestore -x -f -)
you must do this for each filesystem/ disk partition

Also if you want the disk to be bootable, when creating the disklabel
specify the filesystem type, eg.
disklabel -rw -t advfs rz5

John Zawada writes...

dd if=/dev/rrz2c of=/dev/rrz1c bs=64k conv=noerror,synch
Received on Wed Mar 12 1997 - 18:11:54 NZDT

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