Fujitsu MAS3367FC Product/Maintenance Manual page 34

Specifications
Note:
The MTBF is defined as:
MTBF=
Failure of the equipment means failure that requires repair, adjustments, or replacement.
Mishandling by the operator, failures due to bad environmental conditions, power trouble, host
system trouble, cable failures, or other failures not caused by the equipment are not considered.
(2) Mean Time To Repair (MTTR)
MTTR is the average time taken by a well-trained service mechanic to diagnose and repair a drive
malfunction. The drive is designed for a MTTR of 30 minutes or less.
(3) Service life
The service life under suitable conditions and treatment is as follows.
The service life is depending on the environment temperature. Therefore, the user must design the
system cabinet so that the average DE surface temperature is as possible as low.
DE surface temperature: 40°C or less
DE surface temperature: 41°C to 45°C
DE surface temperature: 46°C to 50°C
DE surface temperature: 51°C to 55°C
DE surface temperature: 56°C to 60°C
DE surface temperature: 61°C and more
Even if the IDD is used intermittently, the longest service life is 5 years.
Note:
The "average DE surface temperature" means the average temperature at the DE surface
throughout the year when the IDD is operating.
2-6
Operating time (hours) at all field sites
The number of equipment failures from all field sites
5 years
4.5 years
4 years
3.5 years
3 years
Strengthen cooling power so that DE surface
temperature is 60°C or less.
C141-E198