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<li><strong>File</strong>: "Full" file system archive to online storage before re-building a host (completely reformatting disks and partitions)</li>
<li><strong>System Image</strong>: A complete operating system image to allow either [[cloning]] to new hardware, or full system restoration</li>
<li><strong>Database</strong>: See [[Mysqldump]]
</ol>
== Example Use Cases ==
# and also on Linux, a SIGINFO signal to the process id of a dd process will show you the status, and then continue.
kill -USR1 $(pidof dd)
# a local copy is MUCH faster than a network copy -- getting 17 MB/s instead of ~400 kB/s
sudo dd if=/dev/sda5 bs=4096 conv=noerror of=/media/disk-a/backups/sheila-laptop/acer.image.5
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Backup up ~60 GB of data across a USB 1 interface using rsync and -z for compression will take over 1 day. In fact it will take over 10 minutes to generate the file list. My experience was with 874,490 files.
Similarly, if you are backing up across a network, then you can get dramatically slower results than if the source and target are local. For example, in my most recent backup, I was able to copy 18GB over a wireless network but it took 43,712 seconds (over 12 hours). 19GB over a local USB2 interface took 1,037 seconds (17 minutes).
In most backup scenarios, the first backup is the one that takes the most time.