Why is your 250GB hard drive showing as file system RAW with used space 0Gb and free space 0Gb?
This error is most commonly found with remote HDDs, or USB storage devices. Although it's not an error as such; showing a file system as 'raw' usually means it is unpartitioned and unformatted.
In this state, there is no file system present, there is no distinction between used and free space, and so presents 0Gb for both.
You'll be familiar with your main HDD being C:\
Think of 'C' as being the label for that space. If a 250Gb HDD has one partition, then that partition is 250Gb.
We can partition that HDD further. Let's make one partition of 100Gb, another partition of 100Gb, and a third of 50Gb. We'll label them C, D, and E.
When you look at 'my computer' it will look like you have three HDDs, but really it's the one HDD with three partitions:
Local Disk (C:)
Local Disk (D:)
Local Disk (E:)
For most purposes, you'd just create one primary partition the size of the HDD.
There are two main file systems to format an HDD or other storage device in. FAT32 and NTFS. Think of them as filing systems.
FAT32 is an older file system, used in older versions of windows for example. It is generally less secure than NTFS. There is also a limit on the size of files able to be saved in FAT32.
NTFS is used on the later versions of windows and in current USB storage devices. It has a range of benefits beyond the scope of this answer.
How to partition and format my HDD or storage device:
Right click on 'my computer' and select 'manage'
Select 'disk management'
Select your drive or storage device BE VERY CAREFUL YOU CHOOSE THE CORRECT DRIVE
Right click and select 'partition'. You want to create a primary partition using NTFS. Allow the size to be default.
Once partitioned, right click and 'format'.
Once formatted, it will show as file system NTFS and show accurate used/free space.