PhD student where TA work leaves little time for PhD. Is it even worth it to finish this PhD? Background: I started a PhD in a CS-oriented field about 8 months ago, after completing my masters. At the very start, I was given a lot of duties besides my PhD project, such as responsibility for several of our servers, various software and hardware, user accounts, etc. I also serve as a TA to different courses every semester. After all that, I estimate that in terms of time, 15% of the working week is maybe left for research work. In my project I work alone (this is nice), but my project as well is more ambitious than that of other people, as already confirmed by my advisor and colleagues. 

Problem: I started a PhD with the hopes to research an issue at depth and gain expertise in that field, now I find I don't actually have time to seriously devote myself to research activity. I was apparently hired to be some kind of an "assistant", but not one that should be called "research assistant". On top of all, I'm paid much lower than what I could earn out in the open, or what I should be paid given the amount of hours extra I put in. I am really demotivated because I entered the PhD with different intentions. FYI, I have no desire to continue in academia as a career, neither do I need the "Dr." title to be more marketable or for ego purposes or whatever - the only reason was fun of the kind I get very little.

Question: I can't decide if it's worth it to stay, I also don't want to be spoiled and foolish. I won't take your word as command, but would be nice to just get honest 3rd party opinions, or sharing if you're dealing with the same situation.

EDIT: thanks all for sharing thoughts and giving some advice. I marked as "answer" the comment with the most subcomments. I already talked to other PhD students and it seems most don't have it as tough as me. I guess with all these tasks eventually the quality of my research will suffer, and I will talk to my advisor about this particular point, as I believe this should be a concern for him as well.
Everyone in academic CS gets below market pay. It sounds like they made you a department IT guy, and I've never heard of that, but it may not be too unusual. 

You might be burned out, they overwork you. You can:

1) talk to your advisor about all this. Maybe they can lighten the load. TAing and being an assistant sounds like too much. 

2) take some time off. Go into industry for a year. It sounds like you want to do that anyway. Departments have a process for being on-leave. Make some money, get a hobby, don't think about your research for at least three months. Then decide if you want to go back and finish your PhD.