I did my Grading and drainage test this week at a test center in Houston and requested to have a white board. The ladies at the test center didn't know a physical white board was allowed. I asked for it, and they said no. I persisted, and they said they'd check. Then they said yes and gave me a white board, a marker, and an eraser.
The white board was letter sized; you can write on both sides. The marker looked like a typical classroom whiteboard marker but was almost out of ink. I didn't realize it until I started my test and didn't want to risk getting disqualified to go out and ask for a new one. So make sure you try it when they give it to you. As the marker tip was so thick, you cannot write much on the board. I had planned to keep some calculations and notes for review later on, but couldn't because the board was very small compared to the tip of the marker (and because it was out of ink). I practiced with scratch paper and a pen. In hindsight, knowing what the whiteboard is like, I would have practiced just with the digital calculator and comments functions, and only used the paper when absolutely needed.
Not sure whether situations are different in different test centers, but wanted to share my experience in case it's useful for others.
Also the test room I went didn't seem to have A/C. When I was 2 hours in, one test taker went out to talk to the ladies and they turned on a small fan. It was 86 degrees Texas weather. My first test in the same test center was last December and I remembered the room being cool-cold. So next time I'll bring two sets of clothes and change after I arrive in the test center.