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| 1.7 Reliability |
1.7 Reliability |
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(1) Mean time between failures (MTBF) |
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| Conditions of 300,000 h |
| 250H/month or less 3000H/years | ||||
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| or less | |
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| Operating time | 20% or less of | ||
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| CSS operations | 50/day or less | ||
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| Total 50,000 or less | |
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| Power on/off | 1/day or more needed. | ||
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| Environment | 5 to 55°C/8 to 90% | ||
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| But humidity bulb temperature | |
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| 29°C or less | |
| MTBF is defined as follows: |
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| MTBF= | Total operation time in all fields |
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number of device failure in all fields (*1)
*1 “Disk drive defects” refers to defects that involve repair, readjustment, or replacement. Disk drive defects do not include failures caused by external factors, such as damage caused by handling, inappropriate operating environments, defects in the power supply host system, or interface cable.
(2) Mean time to repair (MTTR)
The mean time to repair (MTTR) is 30 minutes or less, if repaired by a specialist maintenance staff member.
(3) Service life
In situations where management and handling are correct, the disk drive requires no overhaul for five years when the DE surface temperature is less than 48°C. When the DE surface temperature exceeds 48°C, the disk drives requires no overhaul for five years or 20,000 hours of operation, whichever occurs first. Refer to item (3) in Subsection 3.2 for the measurement point of the DE surface temperature. Also the operating conditions except the environment temperature are based on the MTBF conditions.
(4) Data assurance in the event of power failure
Except for the data block being written to, the data on the disk media is assured in the event of any power supply abnormalities. This does not include power supply abnormalities during disk media initialization (formatting) or processing of defects (alternative block assignment).
