Dualboot with windows 8? Problems with partitions

Question

I'm trying to install ubuntu 12.10 on a sony vaio that runs windows 8 natively.

After booting from cd I arrive at the point where I have to choose the partition:
First of all, I come to a page where it tell me to scroll a bar to choose how much space I want to dedicate to ubuntu (like this (not my case)); but it shows me a partition of something like 30 GB.

So I decided to go for the advanced one.

The partition that I expected to use is the sda5, type:ntfs, and 718 GB wide. Under the flag "used" there's the word "unknown".

I was not able to modify/divide that in any way. I also tried to run gparted live cd to divide it manually but I couldn't boot it because of a "safe boot error".

What I am doing wrong?

Answer 1

Chances are the disk needs to be checked with a filesystem-check utility. You'll need to do this in Windows, with the FSCK utility or a GUI front-end to it, since there's no suitable utility in Linux. Once you've done this, be sure to shut down cleanly, since if you just hit the power button, the disk won't be properly unmounted and you're likely to run into the same problem again.

One more point: Windows 8 uses a "fast start-up" feature by default, but this is essentially a suspend-to-disk rather than a shut-down. You must disable this feature when dual-booting, or risk filesystem damage. You can turn this feature on or off in System Settings; see here for details, or do a Web search to find other descriptions.