Air Flow Management (Part 2)

Since we now know what changes we want to make and how to measure their effectiveness, in this episode we'll cover blanking panels, insulation and thermal containment.

Blanking Panels

Blanking panels are known to many as being ineffective, expensive and made of materials that conduct heat really well like, oh i don't know, STEEL! So if that's the case, why would anyone want to use them? While APC, Panduit etc both sell blanking panels in various sizes/quantities and yes, I've used them in the past, I don't like use them anymore for what should be fairly obvious reasons by now.

I was put onto the following company I'm about to mention and since then i almost exclusively recommend plastic blanking panels like those offered by Eziblank. They come in 8 RU sections with the ability to break them apart into a total of 8 individual 1 RU panels.

Almost all blanking panel manufacturers offer tool-less installation and Eziblank is no different. You'll be done and dusted fitting them to a rack in only a couple of minutes.

The Eziblank panels are significantly less expensive than some of the name brand blanking panels with one box of panels able to cover up to 60RU of space! At just over $100 USD a box they are seriously good value.

So far we've talked about some of the benefits in using blanking panels but the main reason you need them, the main reason why you want these in your life is because they help make sure cold air flows from the front of the rack, through a heat load (like a server) and out the rear of the rack. Air that doesn't pass through a heat load is wasted air that will continue to cost you money in energy bills until the end of time itself. Save yourself thousands tomorrow by spending a few hundred today.

Insulation

Sometimes when these rooms are built, noise transfer and thermal insulation aren't even topics that are either considered and/or covered. It's usually assumed that because the room is meant to house servers, there should be no need to worry about it. Wrong!

So what can we do to save us a few dollars on our energy bills? Well to be honest, it's exactly the same as a regular room in your home or office. Everything we look at here and every product we use can be re-used outside of the server room and is probably available from your local home improvement store. If you're lucky, you may be able to use excess materials from elsewhere on the site and cut your costs down to almost zero.

Foam Weather Stripping

Yep, that's what a roll of tape looks like...

Foam weather stripping come in a variety of different widths and lengths. By using them you can seal around doors and windows etc or seal gaps in racks or between racks. Noise transfer to other rooms can be an issue as well that will make everyone outside of IT, hate IT. As an added bonus of using foam insulation tape etc, you'll also be reducing noise transfer between the two areas.

Also available is foam (for lack of a better word) cord in various lengths and diameters. If you have windows that open, you can cut this stuff to length and jam it in the window tracks. The window may not open until removed, but it's a minor inconvenience when compared to the energy savings.

Bat vs Blown vs Foam

It sounds like an alternate version of scissor, paper, rock doesn't it? But we're talking about is insulation inside your walls and ceiling. You could be wondering how this even relates to airflow management? Well, if you have any gaps or holes in your walls (or ceiling), it's likely that your losing valuable cold air to an outside room.

You can use either batt or spray foam insulation in the walls but here's the thing... I'm not sure it makes much sense to use it in the entire room. The rear area behind your server racks doesn't need it because we don't really care about keeping the heat in. I will probably have to return to this statement once i'm able to do some testing.

The ceiling on the other hand can use one or more of the options available. It really just depends on your budget. Focus on the area's above the front of the server racks and you should be able to ensure that the cold air stays inside the room and the hot air outside the room doesn't rear its ugly head within the room.

Thermal Containment

Modern servers draw cold air in from the front, use barriers/ducts to direct the airflow over the components that need to be cooled and exhaust the hot air out the rear. By doing so, the servers make efficient use of the airflow available.

You might be thinking "why don't we do this in our server room?". Well, time and cost are normally a factor but it might also be difficult to sell it to management if you already have a server room that "just works". So if it's difficult to sell the idea of thermal containment, you might be able to slap together a proof of concept for relatively little cost (sometimes free) that will hopefully drive the point home.

Thermal Containment - Proof of Concept

Your going to need some paint sheets or a few shower curtains etc whichever one is cheaper and easier to get your hands on. You'll also need a roll of duct tape, something to cut the tape into strips, a ladder and probably a couple of hours to spare.

You're aiming for something like this, but on the cheap!

At the front of your server racks, you'll need to fill in the gap above them. Use the heavier sheets here. They generally won't have to cover as much area so weight shouldn't be an issue. Tape the sheets to the ceiling and let em hang. Use tape every metre or so and overlap with extra pieces of tape as necessary to make sure the sheets stay there.

For larger areas like  thoroughfares, you will need a lighter sheet like a shower curtain.... Or a crap load of tape whichever you prefer.

For thoroughfares, this is what you're trying to achieve... minus the forklift 

Once your done, you can let the room equalise under its existing AC settings before taking some measurements and giving your stakeholders a walkthrough. Personally, I've gone so far as to turn AC unit off completely to demonstrate how well it can work. Don't do this unless you know your IT loads REALLY well or really stupid. Clearly, i'm the latter.

DIY Thermal Containment

If you've managed to sell your proof of concept, now it's time to get real and luckily, I have a plan for that too.

You'll need angle brackets, self tapping screws and rolls of clear PVC anti static sheet. If you want to take your install to the next level and make it adjustable and removal, add to your list threaded pot magnets, stainless steel washers and wing nut bolts.

Start by cutting your PVC sheet to the shape you need to fill the space. Pre drill and screw the clear PVC sheet to one half of the angle brackets. Screw the brackets into the ceiling and you're done.

If you're trying to take your install to the next level, instead of screwing the brackets to the ceiling, bolt the angle brackets to the threaded pot magnets using a wing nut bolt and washers on both sides of the PVC sheet. Finally attach the entire contraption to the ceiling via the pot magnets.

What? You were expecting more? Make sure you don't cut your sheet too short. A little overhang is better than not enough. You can also heat it with a heat gun to bend it into certain shapes.

Final Thoughts

Remember that you need to be taking measurements both before and AFTER because otherwise you won't know if the changes you're making ACTUALLY WORK. Don't simply take my word for it.. take measurements and take action accordingly.

Air Flow Management (Part 1)

Air flow management in smaller environments has often been a point of contention. Mostly because it's very difficult to realise the benefits in smaller environments or it could be that no one other than you cares.

In this article, we'll discuss different forms of airflow management and various ways to take measurements both before and after. Let's get started.

Everything Starts With Measurements

No, not those kinds of measurements! We're talking temperature, humidity, airflow and the like.

Temperature/Humidity

Everyone usually has some form of temperature and/or humidity monitoring somewhere. This is either cabled to or inside of a PDU, a UPS or an OOB device and that's enough right? Not for us it isn't!

The first thing to determine is where to take measurements from and it's probably going to be different for every site. As a starting point, try to monitor the overall temperature within the room. You'll need a couple of sensors for this because you'll want to take an average across all of them. If you were to accidentally place a sensor in a hot or cold spot, hopefully the average will be levelled out thanks to the other probes and should keep you well enough informed until you are able to fix it.

Next you want to measure at the rack inlet. If your AC system supply air feeds in via the ceiling, you need to place your sensors at the bottom of the rack. If your supply air feeds in from the floor, you place your sensors at the top of the racks. What you're looking to find are the conditions of the server farthest away from the supply air which would then be our worst case scenario.

Next on the list is the supply outlets. Monitoring these with airflow and temperature sensors is a good idea because not only do you know the temperature of the air feeding the room but you also know if one or more are damaged (resulting in reduced airflow), have a restriction (resulting in reduced airflow) or the AC system has failed (resulting in no airflow). If you have redundant AC systems, it's critical you monitor the state of your AC units because you won't know when one of the units has failed. Yes, I've seen it happen and i've never seen the temperature skyrocket that fast before.

You could also measure the temperature of air outside of the room. That information could be used to help you determine how you cool the room. If it's colder outside of the room, you might consider opening a few doors or removing a few ceiling tiles etc. 

Finally, if you're using thermal containment, you may want to do the same in your hot aisle. Personally, i'd just get some cheap mercury based wall thermometers and attach them to the wall. A hot aisle is meant to be hot, so I don't see a need to continuously monitor it especially in a smaller environment.

Now that we have figured out what we want to monitor, where the sensors should be placed and how many we need, we should probably look at some products.

There are a couple of companies who specialise in this area but one that i've been quite happy with is Geist. For a small environment, you can't go wrong with the Watchdog 1200 climate monitor. The 1RU Watchdog 1200 has a couple of built in sensors for monitoring temperature, humidity, airflow, ambient light and sound but also supports up to 16 digital sensors, 3 analogue sensors and 4 IP cameras.

Geist seem to have an unending list of sensors to connect to the system. From water sensors and door sensors to isolated voltage sensors and smoke alarms, it'll make you wonder whether the 1200 is actually enough for you.

Finally, you can go online and try out the web interface for free and even navigate a 3D view of the product. Great products and accessories coupled with the ability to test drive the system made choosing Geist easy.

Thermal Imaging

Thermal imaging is a great way to perform spot checks in your datacentre. Use it to see where your hot spots are, if circuit breakers are close to overload and check seals around doors, windows and hatches. What's best is that it doesn't have to cost thousands of dollars to do it.

Take the FLIR ONE for example which is an FLIR camera attachment for your smartphone. It's portable and BLAAAACK!!! and will provide enough resolution to help you make your next move. At roughly $250 USD you can probably justify the cost of one for yourself and occasionally take it to work when you need to.

One thing an FLIR camera cannot do is predict how airflow, temperature etc will change BEFORE you make changes which essentially leads you to making changes, checking with your FLIR camera and repeating until you get it right.

How do we avoid this? With computational fluid dynamics analysis. Strap yourselves in, because take off  is going to be rough.

Computational Fluid Dynamics (CFD) Analysis

Computational Fluid Dynamics (CFD) is a technique that we utilize in datacentres to model and analyse airflow and temperature changes using tons of math! Yep, math!

As you can imagine, the people who created said math are quite expensive and let's not forget the people who have to program said math into a software package that you or I can't understand anyway. Long story short, it's an expensive piece of software. However, if you can make use of it, it's a much more powerful tool than any of the previous tools I've mentioned so far.

You can use it to determine how air will flow in and around your datacentre, discover hot and cold spots but most importantly, you can make changes like those mentioned below and measure their benefits without spending a cent!

There's a couple of options for obtaining CFD software;

• Hire someone to come in and do it all for you (expect to spend a few thousand dollars)

• Buy the software and do it yourself (expect to spend a few thousand dollars and many months studying)

• Buy some software that kinda does most of it and bodge the rest (Expect to spend a few thousand)

Ok, so the emoji keyboard has nothing to do with airflow management but it does fairly describe the art of the bodge.

Continued in Part 2...

In part 2, we'll discuss how plastic, rubber and shower curtains are going to help you achieve your goals!  Seriously...