Almost everybody has heard about the noise that hard drives can make when they are about to fail. This is a likely indication that time for the drive has come to an end and you will experience a data loss if you do not do something soon. However, what most people (and even some experts) don’t realize is that noise itself can be the cause of a severe hard drive failure and can cause data loss!
This might not be the case when you place a speaker near your desktop or laptop and you’re listening to music at a reasonable volume (the vibrations could make the write/read head of your hard drive jump a tiny bit), but an Inert Gas Fire Suppression System in a data center has been proven to cause hard drive failures.
The phenomenon of noise affecting hard drives was discovered in 2008. By 2009, fire suppression systems started causing hard drive failures. Initially, experts thought the inert gas used in modern fire extinguishing systems was the cause of the problem, however, when they analyzed cases further, they discovered something else.
When the extinguishing systems are set off, the amount of oxygen in the air is reduced, causing the fire to go out in the room. Overpressure flaps are used to limit pressure by allowing the corresponding air volume to be displaced outside the room. Analysis showed that the changes in pressure did not affect hard drives. Also, the temperature drop did not affect the hard drives in any significant way, so, what was the cause for the malfunction of the hard drives and the data loss? It became clear that it wasn’t the gas itself, but the noise that the system creates when the inert gas is pushed out of the system at high speed and pressure.
Typically, there are two main sources for noise: The alarm siren and the nozzles which discharge the inert gas. In several lab tests conducted by Siemens in 2009 and 2014, scientists found that most problems with hard drives occur when they are exposed to noise above 120 dB, but some hard drives experienced problems beginning at 110 dB.
Due to the microscopic tolerances inside the modern spinning hard drive, loud noises can stop them operating and even cause permanent failure. Modern hard disk drives contain up to about 250,000 data tracks per inch. To read and write, the element must be within ±15% of the data track spacing. This means that since more data tracks are now located within one inch, there is almost no tolerance left when the read-/write head is offset due to sound/ noise vibration. It’s no coincidence then that issues began to occur the second part of the last decade, right when modern hard disks began hitting the market.
There have been documented failures in Australia, France and most recently, Romania. In September 2016, a failure took place in the main data center of a bank. The damage caused by the noise was severe. Customers of ING bank in the Romanian capital were not able to use their debit cards, online banking, or execute credit card transactions.
When conducting a test pressure discrepancy, the fire suspension system emitted a loud noise while expelling inert gas. The bank claimed that the noise of the inert gas fire suspension system nozzles reached up to 130 dB, more than enough to knock the hard drive’s physical components out of alignment, putting a few dozen hard drives to a halt, losing precious data in the process. The site went offline and the bank relied solely on its backup data center, located within a couple of miles’ proximity. It took several days to bring back the site online. The experts concluded that the servers were not protected enough to withhold these loud and high frequencies caused by the nozzles when the inert gas was released into the room.
Since inert gas fire extinguishing systems are a necessity for every data center, how can employees in charge protect themselves against such an unwanted data loss? Here are some tips one might consider to protect hard disks against noise related failure and data loss:
- Only use and/or purchase servers and storage systems which have special noise reduction cover attached on the side walls of their racks. Several manufactures now have special doors used in their racks to reduce sharp noise.
- Enclose the drives in noise-proof racks and keep doors of racks shut.
- In case of a fire alarm, try to cover the siren.
- Position siren and gas nozzle locations so that they do not radiate directly on the disk drives.
- Increase the number of suppression nozzles and decrease the spacing between them to decrease their sound levels.
- Use SSDs or tape as storage when possible.
- Make frequent backups and replicate critical data to offsite location or secondary data center.
Even with these precautions in place, a fire can still occur and the system can be harmed. In a case when struck by a fire, water or noise related data loss, look for special help from a professional data recovery expert. Sometimes the system can look almost unaffected, but smoke or other harmful gases could have gotten into the rack or the hard disks and have caused problems, which might not be obvious at first sight.
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