Pipe a Hard Drive Through SSH

Introduction

So, assume you’re trying to clone a hard drive, byte for byte. Maybe you just want to backup a drive before it fails, or you want to do some filesystem data recovery on it. The point is you need to mirror the whole drive. But what if you can’t install a second destination drive into the machine, like in the case for most laptops. Or maybe you just want to do something funky?

What you can do is install the destination drive into another machine and mirror it over the network. If both these machines have Linux installed then you don’t need tany extra software. Otherwise you can just boot from a Live CD Linux distribution to do the following.

Setup

We’ll assume the source hard drive on the client machine is /dev/sda, and the destination hard drive on the server machine is /dev/sdb. We’ll be mirroring from /dev/sda on the client to /dev/sdb on the server.

An SSH server instance is also installed and running on the server machine and we’ll assume you have root access on both machines.

Finally, for simplicity in these examples we’ll name the server machine server-host.

The Command

So once everything is setup, all you need to do is run the following on the client PC:

dd if=/dev/sda | ssh server-host "dd of=/dev/sdb"

And that’s it. All data will be

1. read from /dev/sda,
2. piped into SSH, which will in turn
3. pipe it into the dd command on the other end, which will
4. write it into /dev/sdb.

You can tweak the block sizes and copy rates with dd parameters to improve performance, though this is the minimum you need to get it done.

Conclusion

So Why Love Linux? Because it’s Pipes and FIFOs design is very powerful.