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Is there a quiet, quiet server revolution underway? There's evidence to suggest that, as well as power and cooling, noise is starting to become an issue too.

Noise in fact has always been an issue. Although most data centre managers wouldn't necessarily get all legal, beyond a certain point -- a sustained level above about 85dB -- noise can damage the ears. That level can easily be reached in a typical data centre -- and could be approached in smaller but full server rooms. As one IT manager remarks: "Nothing beats the room full of 80+ 1U servers all equipped with the quad 40mm 10,000rpm turbine fans. Five minutes in that one and your ears start to ring from the high pitched drone." The use of noise cancelling headphones or in-ear phones such as Etymotics inside the data centre is common.

There are good reasons to object to noise in data centres and server rooms. As well as being an indication of wasted energy, noise is bad for you. The American Speech-Language-Hearing Association called it "a pollutant and a hazard to human health and hearing". The UK's Royal National Institute for the Deaf (RNID) says: "If you can't talk to people about two metres away without shouting because of background noise, it could mean noise levels are dangerous." It points out that Noise at Work Regulations say that, if you are exposed to loud noise at work, your employer must have noise levels assessed, and keep a record of the assessment." An indicator of whether it's too loud, according to the RNID, is if you have to wear ear-plugs -- although they don't solve the problem.

And the US Occupational Safety & Health Administration (OSHA) says that the high ambient noise level can permanently damage the hearing of those who spend a lot of time in data centres or server rooms. It said it "requires that employees be placed in a hearing conservation programme if they are exposed to average noise levels of 85dB or greater during an eight-hour workday. The data centre or server room should be monitored for noise levels using either a sound level meter or a dosimeter."

Not only can noise be a health problem, it can affect employee effectiveness too. As one IT manager points out: "We have our own loud server room, and are not only looking for solutions to ease the noise, but to also facilitate communication in it. We have impromptu meetings at times with developers and techs that can last for long periods." He says he's looking for ways that allow a group of people "to communicate without shouting when standing next to each other".

The solution found to this particular problem, apart from meeting elsewhere, which isn't always practical when discussions involve the hardware itself, was to invest in some form of communications equipment that IT staff could wear while in the server room. While this works, it involves yet more expense and maintenance -- and it can only ever be a sticking plaster solution.

Stopping staff from going deaf is not the only reason for thinking about server noise. It costs energy to create noise, so noise levels are intrinsically bound up with the issue of power and cooling -- which is at the top of the agenda for most data centre managers. And since noise is generated mainly by fans and by cooling systems blasting cold air into equipment areas, the lower the power level, the less noise will be generated.

Fans are the major noise generator because they have to run at high speed. The faster a fan spins, the noisier it is. And since racked servers offer the best density in space-challenged environments such as server rooms and data centres, they need to be physically slim. Slim designs result in the inclusion of multiple small-diameter fans that have to spin fast in order to shift enough cooling air. You also want some headroom so that, if one fails, the system isn't compromised. As a result, the noise issue takes a back seat.

Yet it doesn't have to be this way.

It starts of course with the CPU -- the hotter they run, the more cooling they need -- and here huge strides have been made by Intel and AMD to save power and reduce heat generation. But with the ever-increasing demand for computing power, it's unlikely that future CPUs will run much cooler than today's do. Instead any extra headroom created by more thermally efficient materials and technology will be stolen back by CPU designers eager to squeeze more instructions per second out of their products.

Yet there are manufacturers selling enterprise-level equipment designed to be low noise. One company, eRacks, sells servers it claims are "ideal for noise-sensitive and space-limited applications". The company says that it selects and specifies chassis designs specifically for their noise characteristics, including fan placement and location, with the aim of avoiding or minimising noise leakage. The downside is that its quiet servers are designed round VIA slow-clocked processors -- quiet yes, but they won't get as much work done as a full-blown Xeon or Opteron.

Kontron makes what it calls a Quiet 19-inch / 4U Industrial Server, while US-based Nixsys Open Systems sells Xeon and Opteron-based tower boxes that use 120mm cooling fans and which it says are designed to be quiet.

While that's not a huge list of equipment or vendors, there is ameliorative action you can take in the meantime. One IT manager suggested improving the acoustics of the server room by installing sound absorbent ceiling and wall tiles, rugs, and sound deadening panels. He said: "Putting the panels on wheels allows you to move them and create quieter work zones inside the data centre as needed."

Another alternative is to put the servers in a acoustically treated box -- especially if the machines have to live out with the users. NEC sells an enclosure, the Express5800/OfficeRackServer, that it claims is "ideal for positioning beside office desks. The rack features a shutter door and soundproof rubber for absorbing sound, achieving a quietness level of about 40 dB when all servers (up to seven) are operating."

Some see liquid cooling as part of the solution -- and it's certainly quieter. But the added complexity and risk involved has caused most to shy away form it, even though it's several orders of magnitude more efficient at carrying away waste heat.

But it's better to keep people out of the data centre. One IT manager said that, in his 10,000 sq. ft data centre, "we probably have someone in the data centre maybe an hour a day, and that's spread across all groups (Unix, Intel, telecom, networking, backups, and building maintenance). I go down to the server room maybe once a week to swap out a bad drive or something like that.

"If it's a one-time server room setup and install, I'd probably just suffer with the cheap earplugs. If you're spending that much time in the data centre after it's operational, you should definitely look at your policies and procedures, and see if you can change that."

The reaction of data centre managers in practice has been to ignore the issue: if it's a trade-off between lots of noise and heat or too little computing power, most IT managers will tend to accept the noise. One IT manager working for a large bank said: "Noise is becoming an issue, but it's nowhere near as important as the power and cooling issues people are experiencing. And noise is not a criterion we look at when purchasing equipment."

So server makers won't pick up on the issue -- which they could solve by selecting components such as fans and chassis that are inherently quieter -- unless their customers make it an issue. And since noise represents expensive wasted energy, it could be that noise will become part of the buying equation as much as power and cooling now are.

Why not go bang on your server maker's door? Go on: make some noise!