SUMMARY: How to restore a partition table?

From: Nils Ellmenreich (
Date: Wed Jun 28 1995 - 04:21:43 CDT


my original question was how to restore a partition table after a new
label has been written where some partitions are deleted in (no free
hog partition). This happend while installing Solaris on a 2nd disk and
attempting to use the swap partition of the 1st SunOS 4.1.3 disk.

Thanks to

        Dave Mitchell <>

for his mail.

He proposed to use the backup command in the format utility to restore
the old label. BTW, SunHotline in Germany gave us the same answer (we
asked them as well as I didn't get any replies from sun-managers for
three days).

Unfortunately, the proposed solution does not work (I had already tried
it). The reason is that the disk label is being stored several times on
the disk (all of them are equal). If the the primary label gets
corrupted the backup command can restore the label by looking at one of
the backup labels.

In our case, the primary label was not corrupted - there has been a new
label successfully written on the disk. All backup labels matched the
primary one so the backup command showed no effect.

The solution I hoped for was something like doing some arithmetic with
the contents of the superblocks in order to get the old block numbers
of the deleted partitions.

Anyway, through the backup partition we could access the old
root-partition. In there, the suninstall program of the 4.1.3
installation stored the partition data in /etc/install. I've just
created new partitions of exact the same size as before and I had them
back! :-))

But the question itself remains unanswered.



Nils Ellmenreich                         University of Passau, Germany
Nils@Uni-Passau.DE                           Dept. of Computer Science

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