I'm about to backup my f-13 system so I can install CentOS instead. I'd like to determine just how much disk space I need to make a backup so I don't have to buy a new external harddrive right now.


To calculate the size just use:

$ du -sh /path/to/what/you/want/to/backup

It will return the size in human readable format, it should look like this:

$ du -sh .
8.8M    .

Meaning my current directory would require about 8MB to backup.

  • great! But how do I see how much space I need to create an image of my system? Sorry for the poor wording of the original question
    – Ramy
    Sep 5 '11 at 23:34
  • Sure, a really good rough guess will come from 'df' it will show how much space is used on your entire hard drive.
    – polynomial
    Sep 7 '11 at 4:52

Generally, a backup only includes data files.

The way to tell how much space it'll require is to look at your data file folders and add the total sizes up from each. Then give yourself sufficient headroom for future backups, and buy a disk that works.

But if you mean you wish to create an image of one system that you could then use to "go back to" completely from the new OS, then you'll be backing up everything, the entire contents of that OS, and thus you'll need to adjust your size accordingly.

UPDATE response to comment:

Data files as opposed to program files. Program files are files associated with programs and in a home user environment they are not usually backed up.

Data files are files that cannot be replaced simply by reinstalling a program. They contains settings you've set, information you've created or captured. Documents, pictures, music, bookmarks/favorites, etc. They are the files you generally need to keep and thus are the files you back up.

By F-13 I assume you mean Fedora, or linux (Note: If this is the case, please add some tags to your initial question clarifying this). The files you'd backup would be in your home directory or usr directory.

In the second scenario, you're not looking for a backup so much as an image, which is a bit-for-bit copy of the entire hard disk or partition. In this case you'd need a tool to create the image and you'd need a backup harddrive at least as big as the total used size of your current hard drive. I do not recall specifically how to see the total used space of your hard drive in Fedora.

But, with hard drives being as cheap and large as they are, I'd say spend $100-$150 and get a 2 terabyte hard drive. Unless you rip every movie you own and store them on your computer, you're probably not going to run out of space with that.

  • Thanks for the answer. What is the best way to calculate the size for the second method you mention? Also, i'm not sure what you mean by "data file folders". Could you explain a bit what you mean by that?
    – Ramy
    Sep 3 '11 at 14:20

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