|2017-08-22||This is why I love linux!||[linux netcat]||Cloning a hard disk over the network||false|
This is going to be short: My old trusty laptop began showing signs of old age. The screen started flickering, a problem I already knew. Last time, I bought a new screen from Alibaba for ~100€, but wasn't going to spend that much on a three year old laptop.
So, new laptop it is. The Lenovo V110-15IAP looked nice, so I ordered it online. It arrived today, but I wasn't going to spend hours to set up a new OS, copy all files over, check if everything is ok --- and I also didn't have an external drive to hold all files during transfer ... there must be an easier way.
Well, there is, and it's called
netcat and some pipes. Netcat is a nice, simple tool that reads and writes data over the network, using TCP by default (more info here).
I connected old and new laptop via ethernet, booted the old laptop into recovery mode, booted the new laptop with a Arch live USB drive I had laying around, and got to work.
First, the two computers need a network connection. On the old laptop:
[~]# ip addr add 10.1.1.1/24 dev enp1s0f0 [~]# ip l set dev enp1s0f0 up
and on the new laptop:
[~]# ip addr add 10.1.1.2/24 dev enp1s0 [~]# ip l set dev enp1s0
Notice the different interface names. Check connectivity:
[~]$ ping -c 3 10.1.1.1 PING 10.1.1.1 (10.1.1.1) 56(84) bytes of data. 64 bytes from 10.1.1.1: icmp_seq=1 ttl=64 time=2.33 ms 64 bytes from 10.1.1.1: icmp_seq=2 ttl=64 time=2.34 ms 64 bytes from 10.1.1.1: icmp_seq=3 ttl=64 time=2.33 ms --- 10.1.1.1 ping statistics --- 3 packets transmitted, 3 received, 0% packet loss, time 2003ms rtt min/avg/max/mdev = 2.335/2.340/2.346/0.004 ms
On the "receiving" (new) laptop, I made
netcat listen on the network, together with
pv to get an idea of the transmission rate:
[~]# nc -l -p 4000 | pv -pterab -s 117g >/dev/sda
The switches for
pv give us some nice metrics, see
pv(1) for more info. The
117g is the size of the disk, this is necessary to get an ETA and a progress meter.
Now, start the transfer on the old laptop:
[~]# nc 10.1.1.2 4000 </dev/sda
The transfer took around 20 minutes at about 100 MB/s, which means the Ethernet is actually the bottleneck).
After that, I verified the first few bytes of the disk to make sure they are actually the same:
[~]# dd if=/dev/sda bs=1M count=1 status=none | md5sum d4bf772aa861fef76ff777aa52ec6800 -
This output was the same on both machines, which means we are good!
After a reboot, the new machine booted straight into my trusted fedora, and everything worked out of the box (except I had to re-enter the WiFi password, which I guess has something to do with changing MAC addresses). And not even five minutes later, I started writing this post.
I also eperimented a bit with compression (lz4 and lzop), but even though the network was the bottleneck, the transfer didn't complete any faster. Not sure why, but I got what I wanted, so I didn't bother to investigate further.
You could do the same over any network, but with the
netcat transfer being unencrypted, you'd need some kind of encryption, for example by piping through
Anyway, thank you for reading!