Your SSD drive will need >27GB free space on C: to upgrade from Windows 7 to Windows 8, here’s some clean-up tips

Windows 8 system requirements listed here (and above) include the big gotcha: at least 20GB free disk space is required on your C: drive for 64 bit upgrade installs. This is likely to still be the case with the RTM (arriving August 15th).

If you have a workstation-caliber laptop, like my vZilla and its 128GB mSATA SSD, you may find keeping things like a 16GB hibernate file on a 128GB C: drive a challenge.  Staying short of only 10% free space at all times is also a good idea, so you really need more like 25GB for a bit of extra margin, and avoiding potential SSD performance impacts. Especially important on older, non-TRIM enabled SSDs.

So, here’s some methods to get some empty space back, in increasing order of aggressiveness/desperation. If you are uncomfortable doing these actions, you shouldn’t be doing them! Let’s face it, this site is largely for intermediate and advanced users, but the first two are the easiest, safest, and also likely have the biggest impact in free space.

1)  Start with clicking Start, then typing “Disk Cleanup” then pressing enter

  • That’s the easy one, just follow the wizard.

2)  Nuke that big hibernation file properly:

OR

  • Open a command prompt with administrative privileges.
  • Enter powercfg.exe -h off
  • Exit the command prompt.

If you got 16GB of RAM, well, you now have 16GB more free disk space on your C: drive. That’s right, no reboot required, immediate benefit (if you don’t need hibernate functions). Unfortunately, if you choose a power profile that uses hibernate (such as suspend when inactive for 15 minutes, and hibernate after 8 hours), then the hibernate file will come back again.

3)  Change swap to 2GB if you have 8GB or greater in your system, letting Windows manage the size of your swap file gets silly, with double the RAM.
Go ahead and reduce your swap file space, 4GB should be plenty, because if your hitting the swap file that hard, you’re really in trouble as far as speed. Control Panel > System > Advanced system settings > Advanced > Performance > Settings… > Advanced > Virtual Memory > Change… > 
 

4)  Consider moving the My Documents and other user folders:

5)  Manually delete all files (that are dated older than your last reboot) in the temp directory:

  • paste this line into your Start, Search (or Run) box: shell:UsersFilesFolder\AppData\Local\Temp
  • sort the resulting file/folder view by date
  • select everything (files and folders) older than your last reboot (to avoid trying to delete currently in-use temp files)
  • right-click, select Properties, to determine how much disk space you’re about to recover (for some reason, I find Step #1 above often leaves a lot of files here!)
  • hit the Del key while holding down Shift to permanently delete the selected files and folders immediately, avoiding the Recycle Bin entirely
6)  If you use iTunes to do local backups of your iOS device, move them off your C: drive
Those backups can be quite large, and are on your C: drive by default, even if you installed iTunes itself to something other than your D: drive!
  • Read all about exactly how to do this here.
  • In my case, seen in this video below, I free up 18GB of space on my 128GB SSD, by moving my backup of up my 64GB iPhone 5:
7)  If you really are desperate (and have a full backup)
8)  Clean-up (after you make the move to Windows 8)
Once you’re done upgrading, remember to completely backup your system, then remove that Windows.old folder.
I had 27GB of unused C: drive space when I started my install, then had only 2GB when done:
So nuking that Previous Windows installation was certainly critical for me, since mine was 22.1GB (pictured below):
Please comment below, to let us all know how your pre-Windows 8 upgrade cleaning goes! And don’t forget to do a full Windows 7 image backup before attempting upgrades (I’d never trust roll-backs of such major upgrades gone wrong).

Aug 17 2012 Update: My testing with the RTM/GA code shows that you actually need 27GB available!

Feb. 01, 2013 Update: I’ve found that if you use Lotus Notes, you may want to check out this subdirectory below where you have Notes installed, and nuke some old, mysterious huge DMP files: /Notes/Data/workspace/logs

Lotus-Notes-dmp-files-nearly-3GB
And in case you didn’t notice, over time Windows Update Cleanup can get pretty large too: Windows-Update-Cleanup
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  • http://twitter.com/fulviods fulvio di stefano

    Hi thanks for your post. I have a question. I have a 70gb disk on win 7 (with many installed programs) with only 13gb free space (i erased temp files and made a lot of things). I have a 6.4 gb hiberfil.sys file.

    My question is : if I want to upgrade to win 8 and i erase the hiberfil.sys i’ll have 20 gb free space. Its enough to upgrade ? Because i dont know ho to have more free space.

    Thanks

    • http://tinkerty.com/ Paul Braren

      As I wrote in the “Update” section below the original article, it appears that 27GB are actually required. So when you go to run the install with only 13GB available, the installer will refuse to allow you to continue. You’ll also run the risk of degrading your SSD performance, as it’s not good to max out the capacity of an SSD. Sorry, I don’t have a happier answer for you!

      • http://twitter.com/fulviods fulvio di stefano

        if i move some folders (some appdata folders) with mklink (symbolic link) and i erase the hiberfil.sys i could succeed to have 14 more free gb to arrive at 27. Could it be a solution ? thanks for your answers

        • http://tinkerty.com/ Paul Braren

          Possibly, but I’ve found messing with AppData folders risky (mistakes lead to issues), but I haven’t really researched that lately. As far as erasing hiberfil.sys, yes, you can, but it’ll come back again, so go with the method I mentioned above instead. Hope this helps!