[SOLVED]Adding scratch discs to Adobe Photoshop CS5

[vale]

Hello, this is my first question on this forum. I tried searching the topic but couldn't find anything.

I'm running Photoshop CS5 on a Vbox runnig Win7 (32bits), my host is ubuntu 14.04 (32bits also, I think). I'm working on something and, all of a sudden, I'm unable to do anything, because "scratch disks are full". I had happened other times but only after a lot of work with over complex files. Anyway, I went to preferencies to see my scratch disks, and it turns aout I hadn't set up proper ones. PS is using the C: drive (which is the virtual box's OS drive), which is of course tiny for that task.
In my laptop, aside from the booting drive with Linux, I have a data partition and an external drive. Both drives are mounted in the host and the guest and I'm using them to work on VBox.

The thing is, those drives do not show on Edit->Preferences/Performance/Scratch disks, so I cannot set them up as scratch disks.
Do you have any idea why this is and how to solve it?

First of all: I'm not 100% sure the problem is VBox. I just think it is, because I haven't had this problem before, running PS in Windows (real-not VM Windows, that is), and the use of VBox is the only different thing from that and from other people's "scratch disk issues".

I really, really hope you can help me, I use adobe's CS suite a lot for work and study.

Thanks, and please, if I'm wrong and this has indeed been treated before, lead me to that and I won't bother you anymore.

Greets!

[Perryg]

Post a screen shot showing them mounted in the guest.

Use disk manager

[socratis]

Both drives are mounted in the host and the guest and I'm using them to work on VBox.

Exactly how are they mounted? Network share? Shared folder? Do they have a letter mapped? Can PS use network drives as scratch drives?

[vale]

Well, maybe "mounted" is not the word? I'm not native english speaker and not a technician on this stuff.
What I meant is that Vbox can use them: read and write on them. In my VBox user interfase they appear on "shared folders".

Oh, Disk manager is in the control panel, silly me.

Sorry it's in spanish*. But I can see that it lists only the C drive (arranque means "booting", the other expressions I couldn't translate accurately), and not the other towo drives. What do I do now?

*(Arranque means "booting", the other expressions I couldn't translate accurately)

[vale]

Well, finally and after some deduction from the questions before (thanks @Socratis and @PerryG) and some tinkering, I could create and add a SATA drive in the "storage" section of the Vbox user interfase:

Clicking on storage, then on "Controller: SATA" ->add hard drive, and followed instructions without changing any options, it worked (It has to be SATA, otherwise the machine tries to boot from the newly IDE drive and, of course, it can't).
Then I executed the virtual Windows and went to Disk manager, and I formatted that disk and did all the things it asked me to do (again, didn't change any option, went all default), and then reboot and voilà, I get my extra disk for scratch purposes.

As you can see, I'm no technician but, well, I solved it.

I just thought I'd post this so if somebody finds the same problem they can solve it too.