March 17, 2008
Critical Facilities Roundtable Meeting 03/12/08
I attended the Critical Facilities Roundtable meeting on Wednesday, hosted at the Altera campus.
The first 20 minutes were for announcements and other meeting business:
- Charles suggested we pursue research using the power grid as a generator load bank instead of resistive on site load banks. This of course requires power company cooperation and with PGE in the room it put some pressure on them.
- LBNL announced they will be releasing a datacenter profiling tool in May.
- LBNL will release the results of the LBNL and Sun "Chill Off" this summer.
- On Friday April 11 there will be a tour for interested parties of a supposedly Platinum LEED carbon neutral datacenter in Sonoma Mountain Village.
Altera and PGE then discussed the cold aisle containment retrofit of the Altera datacenter in building 3. The datacenter consists of 8-10 rows of 6-8 cabinets with each hot aisle and cold aisle enclosed on one side by a wall. There were four pre-existing air handlers in the room, two DX CRACs and two water CRAHs.
They gathered the following data:
- Temperature probes on the inlet and discharge side of the CRACs and CRAHs
- Four temperature probes in each cold aisle
- Current taps on the CRAC condensers to measure load
- Power draw of each rack
The data showed that:
- Only 40% of conditioned air was used to cool the servers
- They were conditioning 2.6 times more air than necessay
- Server face temperature varried from 68F to 77F
- CRAC delta T was only 12F to 18F
Based on the gathered data Altera believed they could benefit from hot aisle containment. They acheived this by:
- Installing blanking plates on the fronts of all server racks to fill empty rack spaces
- Adding clear vinyl strip curtains on the aisle side of each cold aisle
- Fabricating sheet metal barriers between the tops of the racks and the drop ceiling
- Removing perf tiles from the hot aisles
- Ensuring adequate sprinkler head coverage (two per aisle) in both the hot aisles and cold aisles
- Installing APC InRow RC water cooled air handlers in the high density rack line ups
After the retrofit Altera was able to cut energy use by 44.9KW with an annual savings of 393MWHrs.
Some notes from the Q&A session:
- Altera used polyurethane foam between the metal partition wall and the tops of racks to seal up any open areas
- The APC InRow units are fed by building chilled water and each have their own VFDs for fan speed control and well as electronically operated balancing valve
- The main 30 ton CRAH in the room is used to handle primary cooling and humidity control
- If segregation wall is deemed a temporary structure then there is no requirement to refit the sprinkler heads
- Altera will be using strip curtains with fusible links above the racks in their next build to avoid relocating sprinkler heads
- Sprinklers were already in place above the interstitial area (drop ceiling)
Following the Altera presentation Validus DC gave a presentation on their high voltage DC distribution scheme. Since I've seen this presentation before I didn't take notes. They did mention they have a large datacenter getting ready to deploy multiple 2.5mw pods/modules/colos in their next datacenter. I can only assume this to be one of the big three search engine properties. While there certainly are benefits to Validus's 540V and 48V distribution strategy, I'd rather see 380V DC distribution all the way to each server instead of stepping down to 48V at the row or rack level. This would cut out another stage of conversion and associated losses.
Posted by cary at March 17, 2008 7:19 AM