dd and cp -a

[Karl Larsen]

    I have this computer on /dev/sda and the new hard drive is /dev/sdb. 
This F7 is all in /dev/sda6 and I want to copy /dev/sda6 to /dev/sdb5. I 
tried dd but it failed I think because /dev/sdb5 is smaller 10 GB than  
/dev/sda6 which is 30 GB. It ended with an error message.

    So back to cp -a but there is a hitch. I redid /sdb5 with another 
ext3 file system and I can mount it to /mnt on this computer. So it is 
easy to cp all from /dev/sda6 to /dev/sdb5 but, with a simple # cp -a / 
/mnt it will do all that fine but then want to copy /mnt to the new 
/dev/sdb5.

    Does anyone know a secret that will work? I will read man cp again :-)



-- 

	Karl F. Larsen, AKA K5DI
	Linux User
	#450462   http://counter.li.org.

[Ian Malone]

Karl Larsen wrote:
>     I have this computer on /dev/sda and the new hard drive is
> /dev/sdb. 
>  This F7 is all in /dev/sda6 and I want to copy /dev/sda6 to /dev/sdb5. I 
>  tried dd but it failed I think because /dev/sdb5 is smaller 10 GB than  
>  /dev/sda6 which is 30 GB. It ended with an error message.
>  
>     So back to cp -a but there is a hitch. I redid /sdb5 with another 
>  ext3 file system and I can mount it to /mnt on this computer. So it is 
>  easy to cp all from /dev/sda6 to /dev/sdb5 but, with a simple # cp -a / 
>  /mnt it will do all that fine but then want to copy /mnt to the new 
>  /dev/sdb5.
>  
>     Does anyone know a secret that will work? I will read man cp again :-)
>   
I'm not 100% clear what's missing here.  If /dev/sdb5 is
mounted as mount then copying the stuff to /mnt has copied
it to the file system on /dev/sdb5.  Remount it as / and
you're done surely?

(Aside: I think 10GB might be a bit cramped for a Fedora
install if it's going to hold /home as well.)

-- 
imalone

[Karl Larsen]

Ian Malone wrote:
>  Karl Larsen wrote:
> >    I have this computer on /dev/sda and the new hard drive is 
> > /dev/sdb. This F7 is all in /dev/sda6 and I want to copy /dev/sda6 to 
> > /dev/sdb5. I tried dd but it failed I think because /dev/sdb5 is 
> > smaller 10 GB than  /dev/sda6 which is 30 GB. It ended with an error 
> > message.
> >
> >    So back to cp -a but there is a hitch. I redid /sdb5 with another 
> > ext3 file system and I can mount it to /mnt on this computer. So it 
> > is easy to cp all from /dev/sda6 to /dev/sdb5 but, with a simple # cp 
> > -a / /mnt it will do all that fine but then want to copy /mnt to the 
> > new /dev/sdb5.
> >
> >    Does anyone know a secret that will work? I will read man cp again 
> > :-)
> >
>
>  I'm not 100% clear what's missing here.  If /dev/sdb5 is
>  mounted as mount then copying the stuff to /mnt has copied
>  it to the file system on /dev/sdb5.  Remount it as / and
>  you're done surely?
>
>  (Aside: I think 10GB might be a bit cramped for a Fedora
>  install if it's going to hold /home as well.)
>  
    All that is true but the problem was the of= was smaller than the 
if=. I just checked and dd has my entire F7 copied to the new hard 
drive. I just had to make the partition a small bit bigger than this 
one. It is there and perfect!


    So dd works fine if the partition it is going to (if=) is at least a 
bye larger.

Now to have a big scotch :-)



-- 

	Karl F. Larsen, AKA K5DI
	Linux User
	#450462   http://counter.li.org.

[Ian Malone]

Karl Larsen wrote:
>  Ian Malone wrote:
> > Karl Larsen wrote:
> >>    I have this computer on /dev/sda and the new hard drive is 
> >> /dev/sdb. This F7 is all in /dev/sda6 and I want to copy /dev/sda6 to 
> >> /dev/sdb5. I tried dd but it failed I think because /dev/sdb5 is 
> >> smaller 10 GB than  /dev/sda6 which is 30 GB. It ended with an error 
> >> message.
> >>
> >>    So back to cp -a but there is a hitch. I redid /sdb5 with another 
> >> ext3 file system and I can mount it to /mnt on this computer. So it 
> >> is easy to cp all from /dev/sda6 to /dev/sdb5 but, with a simple # cp 
> >> -a / /mnt it will do all that fine but then want to copy /mnt to the 
> >> new /dev/sdb5.
> >>
> >>    Does anyone know a secret that will work? I will read man cp again 
> >> :-)
> >>
> >
> > I'm not 100% clear what's missing here.  If /dev/sdb5 is
> > mounted as mount then copying the stuff to /mnt has copied
> > it to the file system on /dev/sdb5.  Remount it as / and
> > you're done surely?
> >
> > (Aside: I think 10GB might be a bit cramped for a Fedora
> > install if it's going to hold /home as well.)
> >
>     All that is true but the problem was the of= was smaller than the 
>  if=. I just checked and dd has my entire F7 copied to the new hard 
>  drive. I just had to make the partition a small bit bigger than this 
>  one. It is there and perfect!
>   
Sorry, I meant in reference to 'cp -a'.  Bob Chiodini has pointed
out the -x option would be useful too.

>  
>     So dd works fine if the partition it is going to (if=) is at least a 
>  bye larger.
>   
Typo for 'of='?  It should work if they're the same size (since the
same partition information will be appropriate).  That's the case in
which it will work best.  As others have said dd can move the fs to a
larger partition but you'll have to adjust the fs to match if you want
to make use of the full size.

-- 
imalone

[Bob Chiodini]

Karl Larsen wrote:
>     I have this computer on /dev/sda and the new hard drive is 
>  /dev/sdb. This F7 is all in /dev/sda6 and I want to copy /dev/sda6 to 
>  /dev/sdb5. I tried dd but it failed I think because /dev/sdb5 is 
>  smaller 10 GB than  /dev/sda6 which is 30 GB. It ended with an error 
>  message.
>
>     So back to cp -a but there is a hitch. I redid /sdb5 with another 
>  ext3 file system and I can mount it to /mnt on this computer. So it is 
>  easy to cp all from /dev/sda6 to /dev/sdb5 but, with a simple # cp -a 
>  / /mnt it will do all that fine but then want to copy /mnt to the new 
>  /dev/sdb5.
>
>     Does anyone know a secret that will work? I will read man cp again :-)
>
>
>  
Karl,

cp -ax, maybe.  the man file for cp says:

-x, --one-file-system
              stay on this file system

Bob...

[Steve Siegfried]

Karl Larsen wrote:
>  
>      I have this computer on /dev/sda and the new hard drive is /dev/sdb. 
>  This F7 is all in /dev/sda6 and I want to copy /dev/sda6 to /dev/sdb5. I 
>  tried dd but it failed I think because /dev/sdb5 is smaller 10 GB than  
>  /dev/sda6 which is 30 GB. It ended with an error message.
>  
>      So back to cp -a but there is a hitch. I redid /sdb5 with another 
>  ext3 file system and I can mount it to /mnt on this computer. So it is 
>  easy to cp all from /dev/sda6 to /dev/sdb5 but, with a simple # cp -a / 
>  /mnt it will do all that fine but then want to copy /mnt to the new 
>  /dev/sdb5.
>  
>      Does anyone know a secret that will work? I will read man cp again :-)
>   
 1 - make sure the target partition (/dev/sdb5 from the looks of things) is
     AS LARGE OR LARGER than /dev/sda6.

       You can do this check by:
        $ su                      # become root
        # fdisk /dev/sda
        ...
        Command (m for help): p   # you enter the "p" part at the end
        ...
        Command (m for help): q   # you enter the "q" part at the end
        # fdisk /dev/sdb
        ...
        Command (m for help): p   # you enter the "p" part at the end
        ...
        Command (m for help): q   # you enter the "q" part at the end
        # 

     then compare the "Blocks" column entry for /dev/sda6 and /dev/sdb5,
     making sure the one for sdb5 is larger.

 2 - Make a clean partition on /dev/sdb5:
        # mkfs -t ext3 /dev/sdb5

 3 - Check the partition you just made:
        # fsck -f /dev/sdb5

 4 - Mount the new partition:
        # mount /dev/sdb5 /mnt

 5 - Copy over everything from sda6 to sdb5
        # cd $MOUNT_POINT_FOR_sda6    # probably "/"
        # find . -mount -print | grep -v '^./lost+found' | cpio -pdumva /mnt


Cpio will preserve any hard and soft links it finds and will also
correctly copy any device nodes.  I'm not totally sure you can say that
about "cp -a".  As above, the find command piped into cpio will also
preserve any mount points, but not try to copy the stuff inside the
mount point.  Note also the "grep -v '^./lost+found" part of the pipe
prevents copying over any bad/orphaned files from sda6 to sdb5.

BTW: using dd(1) on two different partitions usually results in the "of="
partition thinking it's the same size as the "if=" partition.  When the
"of=" partition is the smaller of the two, this means trouble later on.
When the "of=" partition is the larger of the two, you'll end up wasting
some disk space.  Most of this kind of issue is fixable in file-system
editors, but these are pretty much "guru only" sorts of tools, too.


Hope this helps'idly,

-S

[Karl Larsen]

Steve Siegfried wrote:
>  Karl Larsen wrote:
>    
> >     I have this computer on /dev/sda and the new hard drive is /dev/sdb. 
> > This F7 is all in /dev/sda6 and I want to copy /dev/sda6 to /dev/sdb5. I 
> > tried dd but it failed I think because /dev/sdb5 is smaller 10 GB than  
> > /dev/sda6 which is 30 GB. It ended with an error message.
> >
> >     So back to cp -a but there is a hitch. I redid /sdb5 with another 
> > ext3 file system and I can mount it to /mnt on this computer. So it is 
> > easy to cp all from /dev/sda6 to /dev/sdb5 but, with a simple # cp -a / 
> > /mnt it will do all that fine but then want to copy /mnt to the new 
> > /dev/sdb5.
> >
> >     Does anyone know a secret that will work? I will read man cp again :-)
> >
> >     
>
>   1 - make sure the target partition (/dev/sdb5 from the looks of things) is
>       AS LARGE OR LARGER than /dev/sda6.
>
>         You can do this check by:
>          $ su                      # become root
>          # fdisk /dev/sda
>          ...
>          Command (m for help): p   # you enter the "p" part at the end
>          ...
>          Command (m for help): q   # you enter the "q" part at the end
>          # fdisk /dev/sdb
>          ...
>          Command (m for help): p   # you enter the "p" part at the end
>          ...
>          Command (m for help): q   # you enter the "q" part at the end
>          # 
>
>       then compare the "Blocks" column entry for /dev/sda6 and /dev/sdb5,
>       making sure the one for sdb5 is larger.
>
>   2 - Make a clean partition on /dev/sdb5:
>          # mkfs -t ext3 /dev/sdb5
>
>   3 - Check the partition you just made:
>          # fsck -f /dev/sdb5
>
>   4 - Mount the new partition:
>          # mount /dev/sdb5 /mnt
>
>   5 - Copy over everything from sda6 to sdb5
>          # cd $MOUNT_POINT_FOR_sda6    # probably "/"
>          # find . -mount -print | grep -v '^./lost+found' | cpio -pdumva /mnt
>
>
>  Cpio will preserve any hard and soft links it finds and will also
>  correctly copy any device nodes.  I'm not totally sure you can say that
>  about "cp -a".  As above, the find command piped into cpio will also
>  preserve any mount points, but not try to copy the stuff inside the
>  mount point.  Note also the "grep -v '^./lost+found" part of the pipe
>  prevents copying over any bad/orphaned files from sda6 to sdb5.
>
>  BTW: using dd(1) on two different partitions usually results in the "of="
>  partition thinking it's the same size as the "if=" partition.  When the
>  "of=" partition is the smaller of the two, this means trouble later on.
>  When the "of=" partition is the larger of the two, you'll end up wasting
>  some disk space.  Most of this kind of issue is fixable in file-system
>  editors, but these are pretty much "guru only" sorts of tools, too.
>
>
>  Hope this helps'idly,
>
>  -S
>
>     
    Thank you. I used the DD if= of= and it worked just fine. A real 
experience that worked. I should have no sim-link problems with dd. It 
just got 150 byte chunks of the from and stuck it in the to.

    Today I will put the copy in place of this and make sure it runs ect.



-- 

	Karl F. Larsen, AKA K5DI
	Linux User
	#450462   http://counter.li.org.

[Jacques B.]

>      Thank you. I used the DD if= of= and it worked just fine. A real
>  experience that worked. I should have no sim-link problems with dd. It
>  just got 150 byte chunks of the from and stuck it in the to.
>
>      Today I will put the copy in place of this and make sure it runs ect.
>
>
>
>  --
>
>          Karl F. Larsen, AKA K5DI 
Unless you have a 10 gig partition on that 30 gig drive and that you
are doing a dd of that partition onto the new drive, I am not
convinced it will work (actually I suspect it will not work - at least
not properly).  Reason being the partition boundaries on that 30 gig
drive would not work on the 10, and the # of inodes in the inode table
on a 30 gig would not work, and I'm sure other stuff would not be the
same.  And dd being what it is, all those things would be part of the
bit by bit copy of the first 10 gigs on that 30 gig drive onto the 10
gig drive.

Browsing your newly created /dev/sdb5 will likely not manifest in any
problems.  But trying to use it most likely will (if not now, later)
cause serious problems.

Jacques B.

[Karl Larsen]

Jacques B. wrote:
> >     Thank you. I used the DD if= of= and it worked just fine. A
> real
> > experience that worked. I should have no sim-link problems with dd. It
> > just got 150 byte chunks of the from and stuck it in the to.
> >
> >     Today I will put the copy in place of this and make sure it runs ect.
> >
> >
> >
> > --
> >
> >         Karl F. Larsen, AKA K5DI
> >     
>
>  Unless you have a 10 gig partition on that 30 gig drive and that you
>  are doing a dd of that partition onto the new drive, I am not
>  convinced it will work (actually I suspect it will not work - at least
>  not properly).  Reason being the partition boundaries on that 30 gig
>  drive would not work on the 10, and the # of inodes in the inode table
>  on a 30 gig would not work, and I'm sure other stuff would not be the
>  same.  And dd being what it is, all those things would be part of the
>  bit by bit copy of the first 10 gigs on that 30 gig drive onto the 10
>  gig drive.
>
>  Browsing your newly created /dev/sdb5 will likely not manifest in any
>  problems.  But trying to use it most likely will (if not now, later)
>  cause serious problems.
>
>  Jacques B.
>
>     
    Well I am about to try. I did have to make sure the partition it was 
going to is larger so it works. It will not work if it is smaller. I 
proved that yesterday :-)

    The new load will be on in about 20 minutes, I hope, and should work.



-- 

	Karl F. Larsen, AKA K5DI
	Linux User
	#450462   http://counter.li.org.