Tips & Advice for my spec/gear

[Oranuworu]

I very recently swapped my tanking spec over to Unholy from Blood. I like the potential of Unholy tanking especially with Bone Armor and the possibility of 100% uptime. In order to get closer to 100% uptime I regemmed from straight +30 stam gems to either +10 dodge/+15 stamina or +10 defense/+15 stamina. My health is still 35.2k unbuffed, and with Horn of Winter I run about 28% dodge, and 22% parry. Here is my armory:

The World of Warcraft Armory (http://www.wowarmory.com/character-sheet.xml?r=Sargeras&n=Oranuworu)

I'm trying to figure out how low is too low to bring my health pool down. I haven't raided with this spec yet but during H ToC Bone Armor was up almost the entire time.

Also any suggestions on upgrades would be greatly appreciated.

[ghromorth]

I suppose you meant ToC 5 man, if thats the case in certain raid bosses(yes gromok and anub) you will get almost 25% of uptime (if not less), the lowest point for health i would say its close to 34k TogC10 and 38-39k TogC25