. Various Thermal Reliability - Cool-Running WD Hard Drives Demonstrate Exceptional Reliability in High Duty C free download

File name Thermal Reliability - Cool-Running WD Hard Drives Demonstrate Exceptional Reliability in High Duty C

Thermal Reliability Cool-Running WD Hard Drives Demonstrate Exceptional Reliability in High Duty Cycle Environments Overview/Executive Summary WD drives are highly reliable because they are cool-running and thus perform exceptionally at high temperatures and high duty cycles. The thermal reliability of WD drives can be quantified by tests that prove this assertion. Test i n g C a t e g o r ies WD performs rigorous testing to generate data that quantify drive reliability at high temperatures and high duty cycles. The tests are divided into these categories: ! Reliability demonstration test (RDT) -- This is a one-time test at the qualification stage, typically with 1000 drives running for 1000 hours, to confirm that a hard drive design meets customer requirements for reliability before going into volume production. ! Ongoing reliability tests (ORT) --These tests are performed weekly during a production run. A sample comprising a certain number of drives is drawn weekly and tested over a four-week interval to ensure that the drives meet reliability requirements. Customer Requirements and Testing In regard to testing, WD customers want to know the details of how we arrive at the numbers we cite in our literature and how these values may affect their operating environments. WD test conditions typically involve a high temperature and a 100% duty cycle. The duty cycle is the percentage of time that a drive is reading, writing, or seeking. So, if a drive is engaged in these activities 12 hours a day, or half the time, then its duty cycle is 50%. The percentage of time a hard drive is used functionally is the functional duty cycle; the percentage of time a hard drive is powered on is the power-on duty cycle. WD typically assumes a power-on duty cycle of 3120 hours- per-year (35.6%) for desktop drives and 8760 hours-per-year (100%) for our enterprise drives. In the latter case, 100% means that the drive is powered on all the time. One way that WD customers measure drive reliability is the mean time to failure (MTTF) value. This is the average time (expressed in hours) that a component works without failure. It is calculated by dividing the total number of operating hours observed by the total number of failures. Develop formulas Use the information to determine MTTF to predict MTTF at a Perform reliability at temperatures customer's life tests and duty cycles anticipated