---
title: Backing up and restoring whole block devices
date: 2015-02-14 08:30:51
tags: [raspberry pi, hardware]
---

SD cards are not really a reliable storage, especially when used
constantly e.g. while sitting in always powered-on Raspberry Pi. Because
of that I've recently needed to perform lots of backup/restore
operations ;) I wrote this script for backing up:

```
#!/bin/bash

if [[ -z $1 ]]; then
    echo "usage: $0 device_to_clone"
    exit
fi

device=$1

timestamp=`date +%Y%m%d`
dest_file="/tmp/$timestamp.dd.xz"

echo "about to clone $device to $dest_file"
echo "ctrl-c or [enter]"
read

sudo umount $device?
sudo umount $device

sudo sync
sudo pv -tpreb $device | dd bs=4M | pixz > $dest_file
sudo sync
```

And this one for restoring:

```
#!/bin/bash

if [[ -z $1 ]] || [[ -z $2 ]]; then
    echo "usage: $0 restore_file.xz device_to_restore_to"
    exit
fi

source_file=$1
if [[ ! -f $source_file ]]; then
    echo "cannot open $source_file"
    exit
fi

device=$2

echo "about to restore $source_file onto $device"
echo "ctrl-c or [enter]"
read

sudo umount $device?
sudo umount $device

pv -tpreb $source_file | pixz -d | sudo dd bs=4M of=$device
sudo sync
sudo eject $device
```

Some of the more fun features include progressbars and making sure you've unmounted the
device properly before ;) This also uses parallel threads to deflate the
data, so the XZ compression should not be a bottleneck on any modern
machine. The scripts above were used to backup and restore SD cards but
will work for any block device, be it an external or internal disk
drive, etc. usage example [remember to use the whole device, not just
its partition as an argument]:

```
./backup_sdcard /dev/sdc
about to clone /dev/sdc to /tmp/20150214.dd.xz
ctrl-c or [enter]

[sudo] password for cyryl:
umount: /dev/sdc1: not mounted
umount: /dev/sdc2: not mounted
umount: /dev/sdc: not mounted
19,6MiB 0:00:02 [9,72MiB/s] [>                       ]  0% ETA 0:52:26
```