FUJITSU MHW2120BS - Manual (Page 33)

1.7 Reliability
C141-E249 1-11
1.7 Reliability
(1) Mean time between failures (MTBF)
Conditions of 500,000 h Power-on time 24H/day or less
Operating time 50 % or less of power-on time
Temperature 5 to 45 °C (DE surface)
Humidity 8 to 90 % (ambient)
But humidity bulb temperature
29 °C or less
Conditions of 300,000 h Power-on time 24H/day or less
Operating time 50 % or less of power-on time
Temperature 5 to 60 °C (DE surface)
Humidity 8 to 90 % (ambient)
But humidity bulb temperature
29 °C or less
MTBF is defined as follows:
Total operation time in all fields
MTBF= (H)
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 drives requires
no overhaul for five years or 30,000 hours of operation, whichever occurs first,
when the DE surface temperature is less than 45
°C. When the DE surface
temperature exceeds 45
°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. The operating conditions of Service life are based on the equal
conditions with MTBF.
(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).