> -----Original Message----- > From: Richard Scobie [mailto:richard@xxxxxxxxxxx] > Sent: Friday, April 02, 2010 3:04 PM > To: Leslie Rhorer > Cc: 'Eric Shubert'; linux-raid@xxxxxxxxxxxxxxx > Subject: Re: RAID Class Drives` > > Leslie Rhorer wrote: > > > I would not expect a hard drive to use any fluid lubricant at all in > > its bearings, although it is possible. Nonetheless, 55C is *NOT* a high > > Google "disk drive fluid bearing". Many current drives use fluid rather > than the previously used precision ball bearings. > > > temperature for any industrial lubricant, dry or fluid. Most petroleum > > based and organic lubricants can easily withstand temperatures well in > > excess of 140C indefinitely. The motor oil in your car's engine is > > subjected to much higher temperatures than that daily, and if it were > not > > for the blow-by of hot gases laden with graphite particles and un-burned > > gasoline from the engine cylinders, the oil would last for many years. > I > > Off topic , but a significant cause of motor oil degradation is > increasing viscocity due to the lighter fractions evaporating over time > at high temerature. This is true. The cylinder walls and head surfaces get *VERY* hot. > > would expect the drives to use delron or teflon bearings, or possibly > > aluminum on brass, without any fluid lubricant at all. Any of these can > > easily withstand close to or more than 200C. > > Prior to the relatively recent practice of disk drive heads being parked > off the surface of the platter, it was not uncommon for drives that > had been run for extended periods, at high teperatures, to not restart > after having been shut down. > > In many cases this was caused by stiction, brought on due to > vaporisation of bearing lubricant depositing back onto the platter > surface. I was aware of the "stiction" problem. I was not aware it was due to bearing lubricant. My impression was it was due to the platter lubricant. -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
