Very Computer

Having created e.g. two partitions of the same size on the hard disks of two
*different* systems, linked by nothing more than their respective network
connections, how do I copy the *raw* data of an *entire* partition over TCP/IP
(i.e. the whole partition such as /dev/hdc6 e.g. to the /dev/hda6 on another
computer "at the other end of the network wire", but without any need to put
both hard disks into the same computer for making the copy, or to make an
image on removable media, to then mount it on the new system and copy the
files individually, or even to care about the format of these partitions)?

Briefly, the way that I'd like to transmit the data (preferably with
standard tools not specific to any particular distribution) is this:

 /dev/hdc6 =cp=> PC1 =TCP/IP=> LAN/Dial-Up =TCP/IP=> PC2 =cp=> /dev/hda6

Thanks in advance for your help (also by eMail to my address below).

Read U soon...

Greetinx

dd if=/dev/hdc6 |gzip --fast >big.img
use nfs/ftp/scp/rcp or whatever to transfer the file
gunzip big.img |dd of=/dev/hda6

you'll want to make the destination identical to the source, same
partition size, block size, etc.

if you can dd /dev/zero across the partition before formating it, it
usually doubles the compression rate(around 4:1).  You probally don't want
to try this with a dial-up and a partition of any reasonable size, it'd
probally be cheaper and faster to mail the drive.....

oh and watch out for the ext2 2GB file size limit  

David Williams
Systems Administrator
Department of Computer Science
/**********************************************************/
today's fortune:
"They know your name, address, telephone number, credit card numbers, who ELSE
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-- Arthur Miller

Quote:> You probally don't want to try this with a dial-up and a partition
> of any reasonable size, it'd probally be cheaper and faster to mail
> the drive...

However, as I said in the earlier message, the one thing I *dont* want
to do is make an *image file*; Id rather like "the network" itself to
be the destination, so I will not need the extra space for storing the
(even compressed) partition anywhere. However I do not know exactly how
it could be done, maybe theres something like a named pipe over TCP/IP?

Thanks in advance for your suggestions.

Greetinx

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Before you buy.

Jayan

 # rsh souce_box dd if=/dev/hdx | dd of=/dev/hdx

Karsten

Quote:> To move hierarchies between machines, use the command

>    cd fromdir; tar cBf - . | rsh remote "(cd todir; tar xBf -)"

> where remote is the host name of the remote machine.

                                                 rudy

]> how do I copy the *raw* data of an *entire* partition over TCP/IP

What do you mean by the *raw* data? Do you want all of the superblocks
inodes etc to be identical? Do you just want the data to be identical?
Do you care if data x on sector y on the first drive and on sector z of
the second?

Ie, be a bit clearer on your demands. The suggestion below will work
if you just want the data, not the detailed drive structure transfered.
(Note you must have the dest machine in your /etc/hosts file and you
must have the source machine in the .rhosts file on the dest machine.)

]> (i.e. the whole partition such as /dev/hdc6 e.g. to the /dev/hda6 on another
]> computer "at the other end of the network wire",

]from the 'tar' manpage on my SGI IRIX 5.3 machine:

]> To move hierarchies between machines, use the command
]>
]>    cd fromdir; tar cBf - . | rsh remote "(cd todir; tar xBf -)"
]>

Note, I would use tar xBpf -, to make sure that permissions were
preserved. I would also probably use the S option.
tar xBpSf -
to handle sparse files properly.
(This assumes you use gnu tar. Otherwise sparse files are expanded and a
1K file can grow to 10M.)

]> where remote is the host name of the remote machine.

(*) At leat GNU tar under Linux - and at least as of when I got bitten by it
a few times and stopped using it (about a year and a half ago).

To answer the original question - use netcat, netcat is all you need.
I've done this trick many a time - it is particularly cool to use it for
cloning DOS/Winxx partitions, booting Linux from Tomsroot (on both source
and target).

--

Though all my neighbors are barbarians, and you are a thousand miles away,
there are always two cups on my table.

Quote:>> To answer the original question - use netcat, netcat is all you need.
>> I've done this trick many a time -

>You know, you could have passed along the command line you used...

Pretty straightforward stuff - just make sure you get the redirections
right - and don't call me if anything goes wrong...