7.5Environmental limits
Temperature and humidity values experienced by the drive must be such that condensation does not occur on any drive part. Altitude and atmospheric pressure specifications are referenced to a standard day at 58.7°F (14.8°C). Maximum wet bulb temperature is 82°F (28°C).
7.5.1Temperature a. Operating
With cooling designed to maintain the case temperatures, the drive meets all specifications over a 41°F to 131°F (5°C to 55°C) drive ambient temperature range with a maximum temperature gradient of 36°F (20°C) per hour. The enclosure for the drive should be designed such that these temperatures not exceeded. Air flow may be needed to achieve these temperature values (see Section 11.2). Operation at case tempera- tures above these values may adversely affect the drives ability to meet specifications.
The MTBF specification for the drive is based on operating in an environment that ensures that the case temperatures are not exceeded. Occasional excursions to drive ambient temperatures of 131°F (55°C) or 41°F (5°C) may occur without impact to specified MTBF. Air flow may be needed to achieve these tempera- tures. Continual or sustained operation at case temperatures above these values may degrade MTBF. The maximum allowable continuous or sustained HDA case temperature for the rated MTBF is 104°F (40°C).
To confirm that the required cooling for the electronics and HDA is provided, place the drive in its final mechanical configuration, perform random write/read operations. After the temperatures stabilize, measure the case temperature of the drive.
The maximum allowable HDA case temperature is 60°C. Operation of the drive at the maximum case tem- perature is intended for short time periods only. Continuous operation at the elevated temperatures will reduce product reliability.
b.
HDA Temp.
Check Point
Figure 4. Location of the HDA temperature check point
28 | Constellation SAS Product Manual, Rev. E |
