The backup tool for Windows 8 has changed. If you want to backup just your user files, you want to use File History, which will automatically synchronize your Libraries and backup to an external location. However, File History cannot backup your whole system, including applications. File History is suitable for making backups automatically in the background, even while you are using your computer.
To backup your whole system, you want to create a restore point. This will make a copy of your entire hard drive, including system and application files. This is not automatic. If you need something better, you will need to look for a 3rd party application.
I would not recommend storage spaces, because some issues in it means that it does not appear to provide some of the benefits we would like. Windows storage spaces is not a backup solution. It is a way to store files on multiple hard drives, as if it was a single storage space. It allows you to combine multiple drives (of different sizes) into a single storage space, as well as to resiliently store files (in case one of the hard drives fails). However, if you only have 1 hard drive added to the storage space, the read/write speed change.
This is because RAID increases the speed of read/write by doing these in parallel over multiple hard drives.
If you used multiple external hard drives (at least 2), then the read/write speed may change. However, Windows 8 Storage Spaces does not allow you to control exactly how the data is distributed, and therefore how read/write speed changes directly. You can only control how many drives are available, and the resiliency type (for the same hard drives, a lower resiliency will have higher read/write speeds). To be sure about read/write speed, you would need a formal RAID configuration - however that requires hard drives of equal sizes. In addition, it appears that Storage Spaces is actually slower for most configurations, than a bare hard drive. Obviously, writing is going to slow down. However there appears to be no improvement in read speed (where we would expect an improvement).
For more information on Storage Spaces, check this article.
File History and Storage Spaces can be used together to backup data resiliently.