Re: ffs can't find superblock

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Tue, Feb 08, 2011 at 09:34:15PM +0100, mortee wrote:
> 
> OK, for a start, I decided to make a backup image of the volume, just in
> case. So I created a VMware system with a virtual disk (sd0) big enough
> to accomodate the full volume to save (sd1).
> 
> I created a disklabel on that virtual disk with a partiton of siye
> exactly the same. I tried to clone the FS, but this is what I got:
> 
> # dd if=/dev/sd1a of=/dev/sd0a
> dd: /dev/sd0a: Read-only file system
> 4+0 records in
> 3+0 records out
> 1536 bytes transferred in 0.076 secs (20210 bytes/sec)
> # dd if=/dev/rsd1a of=/dev/rsd0a
> dd: /dev/rsd0a: Read-only file system
> 2+0 records in
> 1+0 records out
> 512 bytes transferred in 0.011 secs (46545 bytes/sec)
> 
> My questions: is there any difference data-wise between using the raw or
> block devices?

Yes. You'd better use the character device.

> And also why is it failing with that message?

I guess sd0a is at the start of the parititon. You're trying to
overwrite the disklabel.
If you want to backup the whole disk, use dd if=/dev/rsd1d of=/dev/rsd0d

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--