Inside an oil industry datacentre

Early in February, ZDNet UK took the opportunity to visit a datacentre that processes geological information for the oil and gas industry. The facility, operated by Petroleum Geo-Services (PGS), crunches seismic data gathered by a fleet of ships spread across the globe.

The Ramform Sovereign, pictured, is one of PGS's 16 seismic survey vessels. It uses seismic survey techniques to hunt for oil and gas deposits beneath the surface of the oceans. The data gathered generates a 3D picture of the areas surveyed, which are then parcelled off into cubes for analysis — analogous to grid squares on a map.

The generated data is "like a CAT scan of the earth. There's huge amounts of data in each 3D cube, and we process it to fine-tune the internal image and then you can slice and dice it any way you like", PGS's global datacentre manager, Mike Turff, told ZDNet UK. "It's similar to medical scans but we do it on a much larger basis. The more work you do on refining the image, the better and more accurate it is going to be."

Each vessel stores the data gleaned from its explorations and then does a "fair amount of processing onboard — obviously you want to do the quality control out there and make sure it's good enough to properly process, because that's the only time [the ships] will be able to turn around and go back", Turff said.

Once the data is processed, the results are stored on tapes, which are sent to land by helicopter and couriered to one of PGS's 21 worldwide processing facilities. Of these, three are dubbed 'megacentres' and are designed for the most strenuous processing tasks. They stand at the top of PGS's datacentre hierarchy. As part of a planned tour of international datacentres, ZDNet UK got the chance to visit the European one, located in Weybridge, Surrey.

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Want to know more about PGS's 'lunatic fringe' computing? Read ZDNet UK's datacentre tour diary.

Each of these 100 or so boxes hold tapes containing data harvested by the PGS fleet. One box contains around 30 tapes, and each tape holds around 500GB of data. If all the pictured boxes contain 30 tapes, that adds up to 1.5 petabytes of raw storage capacity.

The tapes are stored in a separate mini-datacentre on site for redundancy purposes, before their data is sent to the main processing hall for analysis.

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Want to know more about PGS's 'lunatic fringe' computing? Read ZDNet UK's datacentre tour diary.

The processing hall consists of around 104 racks distributed across 5,737 square feet. The hardware is predominantly powerful one rack-unit (1U) servers. "Because we're HPC [high-performance computing] we mostly use 1Us from the major vendors — HP, Dell, Lenovo. The 1U is the most cost efficient, generally run, with dual processors at six cores each," Turff said.

A wander round the datacentre mostly found Dell PowerEdge R610s, 1950s and a few Xeon ThinkServers. Storage-wise, there was an even spread of IBM System Storage D553300, FC5820s and some Dell Panasas.

For compute jobs, PGS had considered using specialised field-programmable gate arrays (FPGAs) for certain graphical processing tasks, but the rate of development in Intel systems was too high for FPGAs to match cost effectively, Turff said.

"[FPGAs] can do a fantastic job, but by the time you've done the development, Intel has added a bunch of cores and brought the performance cost down," he said.

The megacentre was opened on November 2008 to replace a 15-year-old facility. "It's been remarkably trouble free, but when you design it from scratch, it's a lot easier to deal with than datacentres that are very old," Turff said. The facility was designed by Keysource, a datacentre specialist contractor.

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Want to know more about PGS's 'lunatic fringe' computing? Read ZDNet UK's datacentre tour diary.

Inside the heat aisle corridor, temperatures can climb to as high as 49°C. This is partially because of the intensity of the jobs run by the servers, Turff said. Typical co-location facilities run at around a 5KW drawdown per rack, but PGS runs at between 15 and 20KW, due to the relative power-intensity of its high-performance computing specification servers, he added.

The hot air rises and is conducted through an overhead plenum into an adjoining sequence of interconnected rooms, then it is pushed back into the datacentre to be drawn through the front of the servers.

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Want to know more about PGS's 'lunatic fringe' computing? Read ZDNet UK's datacentre tour diary.

After the air has left the rack cabinets, it travels across the plenum above the megacentre's ceiling. It then comes down into a room filled with filter bags (pictured), through which it is strained.

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Want to know more about PGS's 'lunatic fringe' computing? Read ZDNet UK's datacentre tour diary.

Once the air has passed through the filters, it is sped by the fans through a watercooled grate and back into the datacentre.

The water is cooled by an exterior adiabatic cooling system, which circulates water through a large radiator-esque arrangement of pipes on the exterior of the facility. It then goes through the plumbing of an 800KW chiller — which only kicks in when ambient air temperature goes over 26°C — to the end grate, where it is then re-circulated back to the exterior cooling.

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Want to know more about PGS's 'lunatic fringe' computing? Read ZDNet UK's datacentre tour diary.

Eventually, the air returns to the datacentre through the grilles. The pressure toward the grille end of the datacentre is kept at 5 pascals above the ambient pressure level to ensure that the air makes its way through the datacentre and back toward the servers.

Each of PGS's megacentres has expansion capacity for 100 percent of their current size, Turff said, and expansion for the Weybridge facility will occur once demand scales enough for it to be necessary.

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Want to know more about PGS's 'lunatic fringe' computing? Read ZDNet UK's datacentre tour diary.