problem with dd and usb drive

[Craig White]

On Fri, 2005-11-18 at 20:40 +0000, Kahn Seidl wrote:

> >From: Craig White <craigwhite at azapple.com>
> >Reply-To: For users of Fedora Core releases <fedora-list at redhat.com>
> >To: fedora-list at redhat.com
> >Subject: Re: problem with dd and usb drive
> >Date: Fri, 18 Nov 2005 12:07:42 -0700
> >
> >On Fri, 2005-11-18 at 18:55 +0000, Kahn Seidl wrote:
> > > I have a problem, i have a fat32 usb drive, which im using to back up a 
> >dns
> > > server.
> > >
> > > i first started to use cp -r * /mnt/usbdrive
> > >
> > > then i stopped, and wanted to do it a better way
> > >
> > > so i did a dd if=/dev/hda1 of=/dev/sda1 bs=1024k
> > >
> > > it finishes too quickly and says 47+1 in    47+1 out
> > >
> > > and now when i ls the /mnt/usbdrive
> > >
> > > I get all sorts of garbage, lots of ?s and such.  and numbers.  when i 
> >try
> > > to delete it, it says its a read only drive.
> > >
> > > also to note, that at first, fdisk said there was one partition as 
> >fat32.
> > > nwo there are several and i have no idea how they got there.
> > >
> > > the last thing is this - i can now not umount the /dev/sda1  it says the
> > > device is busy, eject doesnt work either.  I turned it off, and i still 
> >cant
> > > unmount it, what should I do?  i really dont want to reboot it, it is 
> >our
> > > dns server.  so?
> > >
> >----
> >I hope that there wasn't anything on the dos partition that you wanted
> >to keep since it is now toast.
> >
> >running dd like that did what you told it to do...over writing
> >the /dev/sda1 partition with a copy of whatever was on /dev/hda1
> >
> >I suppose issuing the 'mount' command would tell you what was
> >on /dev/hda1
> >
> >You probably have no choice but to clean up the usb drive with fdisk...
> >
> >fdisk /dev/sda
> >as at least the first partition has been clobbered.
> >
> >h # help
> >p # print (though this might be phony since it will read the
> >            partition table and the contents may not match)
> >
> >Craig
> >
> >PS...You might have had an easier time of it if you had just done...
> >
> >dd if=/dev/hda1 of=/dev/sda1/backup_device_hda1.dd-file
> >
----
> the thing is, that I did use fdisk, and no matter what I did, 
> the partition 
> table wouldnt stay.  i then plugged it into a windows machine, and, explorer 
> crashed, and wouldnt read anything everytime i plugged it in.  it found a 
> new harddrive.
> 
> i would add it to just one file but, ...  it is fat32 , so no files above 4~ 
> gb
> 
> but, it may just work anyway.  is there way I can break it up into 2 files?
----
I haven't a clue why you would want the partition to be fat32 - but if
you want to keep the partition at fat32, the only thing you can do is
write files to existing partition. Otherwise, you are overwriting the
entire partition and then the partition tables aren't going to be
working.

fdisk has a 'w' option to write the partition tables.

You would then have to make a file system on the newly created
partition, either with Windows or Linux (linux uses mkfs).

You could probably split the files but for what purpose? dd has a
'count' option along with 'bs' option, you could make it split the 'out
file [of]' into pieces. Either way, restoring is going to be a bear the
way you are going.

Craig


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