HIGH PERFORMANCE COMPUTING


“We speak with a customer before we deliver a solution to try and find out where they might have holes in their expertise or staff”


UPS systems also help to reduce the


necessity of maintenance by preventing power spikes and noise from reaching the delicate systems – as Leo Craig, general manager at Riello UPS comments. ‘A UPS is really an insurance policy against a number of potential problems. The first main thing is to insure against power outages on the grid or locally, so that the HPC system is unaffected. It also protects the main supply from things like surges, spikes, high frequency noise and frequency variation.’ ‘Things like spikes and high frequency


OCF datacentre


it. The HPC guys have decided that they want to put it on the system, so they can use a portion of the service credits that have been bundled into the SLA – so we will dial in and roll out that kernel patch with them.’


‘It might be that we have discussed it and decide that this is a serious piece of work – we are going to take the whole platform down, and then we will come on site to spend a few days with the customer during this maintenance window. Together as a team we will deploy these fixes or apply upgrades – whatever it might be. ‘This kind of work would usually be decided each quarter, but it can vary based on an organisation. OCF can offer anything from HPC hardware to a fully managed service, so it is important to understand the customers’ needs and manage expectations accordingly. ‘Some customers want a HPC system,


but they only have users and not an admin team. We will act as a virtual system administrator and an on-site admin that can do everything,’ added Slack.


Finding a balance As with so many aspects of HPC, it is about finding a balance – in this case, between the technical staff available to manage a service and the number of


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users. ‘We speak with a customer before we deliver a solution, to try and find out where they might have holes in their expertise or staff. We do not want to add extra work or extra wheels to this system that might slow them down,’ explained Slack.


‘If they have got a good team of


technical staff and they are ‘au fait’ with how to do this, then we can step back and wait for them to request something. We can be as hands on as they want us to be,’ said Slack.


Preventing damage Preventative maintenance helps HPC operators avoid some of the downtime from failed components, but in some cases this can be unavoidable. In these situations it is important that there are proper steps in place to mitigate lost time and recover data. While individual, random component


failures are a potential issue for any system, one thing that cannot be allowed is a loss of power, which would require a HPC system to shut down and abandon any jobs currently running. To avoid this, supercomputers will rely on a uninterrupted power supply (UPS), which ensures power to the computing elements.


noise can actually shorten the lifespan of computing equipment, because the power supply and the circuits are completely bombarded by this noise. It might not cause an instantaneous failure but it will build up over time and then you will end up with an infantile failure on servers,’ added Craig.


Something as simple as flicking a light


switch can cause a small power spike that will travel through the mains supply of a building, diminishing as it travels. However, if it was to hit a sensitive piece of equipment it might cause damage. ‘If we look at the other end where the national grid are doing what is called ‘grid switching’ to manage the power that is sent to computer facilities,’ said Craig. ‘That is becoming more prevalent


because of the introduction of renewable energy into the grid. Instead of having a few large power stations we have got lots of smaller generators like wind or solar farms.’ ‘Renewable energy is causing a problem


for the national grid in terms of much more frequent grid switching and that grid switching creates noise and spikes which is damaging to computing equipment.’ Craig also noted that UPS systems may


begin to play a more important role in the future as stricter regulations are brought in on the use of diesel generators. ‘They are big engines emitting large amounts of CO2


and pollutants. While the latest ones meet current


EU standards, the generators installed in datacentres might not be new – they could be five to 10 years old,’ concluded Craig.


June/July 2018 Scientific Computing World 5


OCF


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