SUMMARY: problems cloning system disk

From: José Carlos Pérez Ramilo (
Date: Mon Aug 09 1999 - 02:13:19 CDT

Here is the summary to my question attached at the end.

Thanks to:

Arthur Darren, Ronald Loftin, Adam and Christine Levin, Kris Briscoe,
Mike DelMarco, Jay Lessert, Patrick R. Demorais, Kevin Sheehan,
Frode Stromsvag, Tony Garner, Sandor Bolla, Dan Stromberg and
Simon Rahilly.

I had run into several things:

- I need to use dd allways with rdsk devices. The man page states
that dd will not work with files beyond 2Gb. I have used it for years
with small (<2Gb) filesystems and never noticed that.

- Of course, the man page for fsck says something similar, but I was
confused: when I run dd with a dsk device, he tells me that is using
a rdsk device, changing automatically.

- The poor performance with ufsdump seems normal. People suggest
using a utility called fastfs.c, from
Looks interesting: it changes some obscure parameter of the kernel
related with delayed I/O in filesystems.
I will test it but not in production environment :^).

- Dan Stromberg suggest not to clone system disks, but autoinstalling.
I will try to find out more about its usefulness for me.

- Other people suggested using disksuite, attaching the new disk, making
a new mirror device with system disk, waiting for resyncronization, and then
unattaching the mirror disk. It might work for sure. I will test it in
another machine.

My cloning script is now:

/usr/bin/dd if=/dev/rdsk/c0t0d0s0 of=/dev/rdsk/c0t3d0s0 bs=2048k
/usr/sbin/fsck -y /dev/rdsk/c0t3d0s0

and I run it every night at 3:00 AM.

Thank you all for your responses!!

José Carlos Pérez Ramilo
Ingeniero de Proceso
Dalphi-Metal España, S.A.
Tlf: 986-293129
Fax: 986-293117

Original message:

> Hello managers:
> I have a problem trying to clone one 9.0Gb system disk into
> another with same geometry (everything in the partition table
> is the same).
> Environment is a UE450 with Solaris 2.6 5/98. System disk is
> c0t0 and the new one is c0t3. System disk only has 2 partitions:
> c0t0d0s0 is / with 7.2Gb, and c0t0d0s1 is swap with the rest.
> I have tried some things:
> # dd if=/dev/dsk/c0t0d0s2 of=/dev/dsk/c0t3d0s2 bs=2048k
> read: Invalid argument
> 1023+0 records in
> 1023+0 records out
> It only copies 2Gb (2048 k* 1023) aprox (/ uses 4.5Gb aprox)
> # fsck /dev/dsk/c0t3d0s0
> ** /dev/dsk/c0t3d0s0
> CANNOT SEEK: BLK 16835360
> I have used several block sizes, and even dd partitions one by one.
> In every case, fsck gives that error, and I cannot mount them. I have also
> tried with rdsk device names without success.
> The I tried ufsdump:
> mount /dev/dsk/c0t3d0s0 /mnt
> ufsdump 0f - /dev/rdsk/c0t0d0s0 | (cd /mnt;ufsrestore xf -)
> and the transfer speed is really SLOOOOW: 5 Mb per minute.

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