Installing Kittens In Your Rack – Data Centre


If you have just taken delivery of your first set of kittens ready for deployment in your rack or you are thinking about ordering then I’m hoping to give you all the info you need to get them fitted. It’s not a difficult process and the installation guide will talk you through the basics but there are a few tips that I want to give you to help along the way.

One of our limited edition black kittens in a rack.Optimal kit installation:

  1. Our recommended kit for a rack would be a 8 temperature sensors, 1 temperature and humidity sensor and 1 gateway. This is to give you the best coverage and  the best visibility of your rack on the heat map.
  2. Fixing your kittens – We have found that it’s best to use the cable ties provided for the data centre environment. It’s warm and dry so it’s not the best conditions for sticky pads, they will work but we prefer the reliability of the cable ties. The doors on the front and back of the racks should be easy to slip the cable ties through.
  3. 4 of the kittens should be placed at the front of the rack equally spaced from top to bottom in order to get a full spread of temperatures to see whats going on in the whole rack.
  4. 4 of the kittens should be placed in the same way from top to bottom in the back of the rack.
  5. If you have purchased a humidity monitor then try fixing that in the top of the rack to see whats going on overall.
  6. The gateway is going to need power and an ethernet connection. You will be provided with a normal UK plug socket for the power, if you require power over ethernet then just let us know (extra cost).
  7. The gateway will need to be fitted within the rack for best signal, it can be sat on a shelf, on top of a server or better still attached to the top of the rack with cable ties.


  1. The kittens sense the temperature from their faces so make sure you face the kitten in the direction that you want the most sensitivity.
  2. Rename the kittens when you get them so you can easily know where they live. You can do this by clicking on the kitten and editing the name (you can also add notes to the notes field).
  3. If you aren’t sure which kitten you have in your hand at any one time just push the kittens nose, till the LED lights up (red for the normal temperature sensors and green for the humidity sensors) and it will flash up on your account.
  4. Don’t forget that you can move the kittens about as much as you like. If you have a problem area in a rack you could alway re group them all around a few machines for a few days or weeks to see whats going on. Just don’t forget to change the names of the kittens and change the heat map so you can see exactly whats going on.
  5. Try playing around with different view for your heat map like the rack views from the front or back, different analytics and even hot or cold alerts to get the best out of your purr account.

If you want some ideas about the kind of insights you can get from the information check out our previous blog: Using onboard monitoring? Here’s four things you’re missing.

Using onboard monitoring? Here’s four things you’re missing.

IMG_3382If your server, rack or cage is in one of the UK’s established and well run data centres you can probably guarantee that they are going to keep the temperature within a fairly well controlled temperature range (unless something goes very wrong).

You also probably already have onboard temperature monitoring in your servers, disk arrays and switches so I bet you have never thought about any other type of temperature sensing or even mapping.

But if you’re simply looking at onboard data the chances are you are actually missing out on a lot of interesting, actionable information. Lets talk about the useful stuff that we at Purrmetrix can help you learn.

1. Locating a Hot Spot.

When you look at your onboard monitors you get a number on a screen – maybe even a graph. But how – and where – does that fit in to the bigger picture and I mean that literally. By putting data into a heat map you can see instantly how that all fits in. Is the machine you are looking at the actual problem? Is it a wider issue in the rack with air flow? Is it one of the machines next to it? A picture paints a thousand words after all. You could use this information to help you to make a better informed choice about where to fit your next piece of kit or how to set up the next rack you buy. Untitled 2 (1)

2. Tracking access to racks

If you have 3rd party engineers accessing your kit for maintenance, replacing kit or just remote hands from the DC to check something out for you wouldn’t you like to know bit more about what they are up to? When they opened the door, which racks they accessed, how long they left the door open for while they walked away from the DC floor or even if they left the doors open when they left. Yes the data that you get from the kittens really are that sensitive as the picture below shows.Screen Shot 2016-07-12 at 10.29.24

3. Remedying problem rack conditions

So what can you tell from the kittens that we believe can help you find out a bit more about whats going on when a fault occurs: if the temperature of the air coming into the rack has risen, if the air flow is being obstructed, someone has been into your rack, the humidity (only with the temperature and humidity monitors) has got up which could suggest a leak or a liquid spill, heat from a next door rack is effecting your rack etc. You could set up alerting in your account so that you can be informed when things go out of your preferred parameters.

4. Analysing what went wrong

Lets say that you had a total network meltdown and you really didn’t have time to study exactly what was going on in your rack regarding temperature. That’s ok because you can go back and replay the data when you have the chance. You might not have been able to figure out what happened or why. Perhaps the same scenario keep cropping up and causing a disk to fail or kit a server to reboot. You could find that there is some small event that is causing the issue or even that now you know how it shows up on the data you could recognise it sooner, set up an alert and stop it from causing the issue before it starts.

The importance of time and space.

There are a lot of possibilities but only with the correct level of monitoring. To make sense of the data you need to have information on where it is coming from, as well as when, and you can’t get this just from your onboard sensing. It’s time to bring our thinking up to date.

kitIf you think all of this sounds interesting then ordering a starter kit would be great place to start. A medium bundle contains 1 gateway and 8 kittens, this would do the trick for one rack with 4 in the front and 4 in the back spaced equally from top to bottom. If you want to have a chat to us about your current step up, problems you think you may have and how best you can detect them using kittens then you can contact us on 01223 967301 or

Liz Fletcher is Purrmetrix’s project manager. After nearly a decade in IT, miles of cabling and gallons of tea she is currently dividing her time between Purrmetrix and the UKNOF Programme Committee.





Hotspots. Real data on rack cooling.

Since last year we have been running a few pilots investigating cooling in data centres across the UK. We now have nearly 15 months of highly detailed data on cooling in racks from different data centre locations that include standard servers, blade servers, hard discs, switches and even a bunch of Mac Minis and it seems like a good idea to share a bit of what the data is telling us.

Health warning: these are pretty preliminary ideas on what is, after all, quite a small sample of data. We’ll need more sites and more time to confirm these hypotheses. But now seems like a good time to take stock and see if we can answer some of the simple questions and think about where we could go with this approach.

It’s also likely data centre professionals are going to want to ask more sophisticated questions than we have about cooling and environmental monitoring from this data: we’ve listed a few  ideas for investigation below and as we add more sites and data we’ll come back to these.

Rewind: what’s Purr all about?

Here’s an Internet of Things recipe we love. Take some very dull data (let’s say temperature). Add a few bits of context (try time, exact location and location relative to other sensors). Sprinkle it with Internet Sauce and voila! Information…to inform decisions and help people decide what action to take next.

For Purr, these actions are about making HVAC more efficient. We think it’s a bit crazy, in the age of the IoT, that most data centres are using three times more cooling capacity than they need. We also think that looks like an expensive problem, or maybe an opportunity.

Temperature in server rack 1

Context for the data: What and where are our pilots?

For practical and ethical reasons (we have an absolute ban on publishing identifiable data without customer clearance) we won’t go into where these pilots are.

There are five test racks, instrumented with 6-8 temperature sensors and a gateway. All of them are in co-location facilities in the south-east of England sitting alongside other customers’ racks.

Data centre temperatures: what does the data tell us?

A few big stories jump out: after several months, the most noticeable feature is the difference between the best and worst performing racks over time. Our champion rack held a mean temperature of 20.6 degrees with less than a degree of variance throughout monitoring. On the other hand we had one rack whose mean temperature of 20.27 obscured swings of over 16 degrees during the trial including peaks over 31 degrees.

Our sensors also revealed the gradients in the racks – ambient intake temperatures change at different levels. Again this was much more pronounced in some facilities than others, with one rack showed a gradient with a 4.4 difference on the intake side. Others had a much tighter range – down to 0.2 of a degree.

Here’s a quick summary of the data from the trial:

Temperature for server racks

Why mean data can be mean – the stories behind the numbers.

Averaging or looking for max/min data obscures some of the interesting stories, which can easily been seen from a heatmap and graph. What, for example, happened on this afternoon?

Server rack temperature showing open door 

In this case, we know: that sharp fall in temperature is characteristic of someone opening the door of the server rack while they work inside.

This one is more mysterious: why does this cold side suddenly develop a hot spot? Is it a variation in air pressure in the facility? Some equipment slipped inside the rack?

Server rack temperature in datacentre 1

What’s next – more questions. More data

Clearly we have a long way to go before we have enough data to undertake the sort of detailed analysis that say, Backblaze can do. (Oh how happy that would make me!) 

But already there is a queue of things on our bucket list for investigation. Which include: 

  1. Can the delta between intake and exhaust tell us anything useful about type of equipment and the type of work it is doing?
  2. Can it give us a useful indication of where a rack has excess capacity?
  3. How many short excursions out of recommended operating range should be tolerated?
  4. Is there a characteristic pattern of temperature change that shows when air is mixing?

If you have questions about the effects of temperature on your server, hard disc or switch please let us know, we’d love to add to the list.

Better yet, if you have a site where you would like to know more about temperature changes then join our beta programme and we’ll install Purr and work with you to analyse the data.


This is the first in a series of posts called ‘Data (Centres), meet Information’ in which we share what we’re learning from our installations. We’re hoping to foster some discussion about the best ways to use information to improve Data Centre efficiency. We’d love to hear your thoughts – whether it’s on better ways to do this or if you think we’re barking up the wrong tree.