When you remove certain defective Field Replacable Units (FRU) from a fully functional CERES DBox, the FRU must be replaced within a specific span of time, after which the effects of the removal of the FRU can cause failures in other components of the CERES DBox. Removing some other FRUs such as the Front Fan Module for any length of time does not cause any cascading failures in the CERES DBox.
The table below gives the window of time available for replacement of various FRU after removal.
Removed component |
Ambient Conditions |
Time to failure |
Critical Component Status |
---|---|---|---|
DTray |
35°C at sea level |
15 mins to E1.L SSD failure |
When DTray 1 was removed, E1.L slots 2 to 8 failed. When DTray 2 was removed, E1.L slots 16 to 21 failed. |
25°C at 10,000 ft |
20 mins to E1.L SSD failure |
||
Front Fan Module |
35°C at sea level |
30 mins, Pass |
U.2 Temp temp 64C, Margin 6°C. |
25°C at 10,000 ft |
30 mins, Pass |
AOC temp 68C, margin 7°C. |
|
Front Fan Module + U.2 Sled |
35°C at sea level |
4 mins to U.2 SSD failure |
When the top layers of U.2 SSDs were removed, both bottom layers of the U.2 SSDs failed. When the bottom layers of the U.2 SSD were removed, the top layers of the U.2 SSDs remained in spec for at least 30 mins. |
25°C at 10,000 ft |
10 mins to U.2 SSD failure |
||
E1.L SSD |
35°C at sea level |
30 mins, Pass |
AOC Temp 71°C, margin 4°C. |
25°C at 10,000 ft |
30 mins, Pass |
AOC Temp 71°C, margin 4°C. |
|
PSU |
35°C at sea level |
30 mins, Pass |
AOC Temp 71°C, margin 4°C. |
25°C at 10,000 ft |
30 mins, Pass |
AOC Temp 71°C, margin 4°C. |
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