Chapter 1
System Architecture
17
Airflow is controlled and optimized over the power supply by using the power
supply chassis as the air-duct for the power supply, ensuring that there are no dead
air spaces in the power supply core and increasing the velocity flow (LFM) by
controlling the cross sectional area that the mass flow travels through.
Airflow is controlled and optimized over the RAID I/O board and HIM in a similar
manner. The controller cover is used as an air duct to force air over the entire
surface of the controller from front to back, ensuring no dead air spaces, and
increasing the velocity flow (LFM) by controlling the cross-sectional area that the
mass flow travels through.
Cooling for all hot components is passive. There are no other fans in the system
other than the fans contained in the power-and-cooling module.
Airflow
Caution –
To allow for correct airflow and cooling, use an air management module
for removed FRUs. Do not leave a FRU out of its slot for more than two minutes.
As noted above, an enclosures cooling system includes four fans in a tandem
parallel array. These variable speed fans provide low noise and high mass flow
rates. Airflow is from front to back. Each drive slot draws ambient air in at the front
of the drive, sending air over the drive surfaces and then through tuned apertures in
the chassis midplane.
Note that the airflow washes over the top and bottom surface of the disk drive at
high mass flow and velocity flow rates, so both sides of the drive are used for
cooling. The airflow system uses a cavity in the chassis behind the midplane as an
air-pressure equalization chamber to normalize the negative pressure behind each of
the disk drive slots. This mechanism together with the tuned apertures in the
midplane behind each drive assures an even distribution of airflow and therefore
LFM for each drive slot. This even cooling extends the operational envelope of the
system by ensuring no “hot” drive bypass.
Further, airflow is “in line” with the top and bottom surfaces of the drive to reduce
back-pressure and optimize fan performance. All of the mass flow at room ambient
is used for cooling the 12 disk drives. The high velocity flow helps to lower the
thermal resistance of the disk drive assembly to ambient temperature. The thermal
temperature rise of the disk drive is dependent upon the power consumed by the
disk drive, which varies by drive model as well as the level of drive activity.
Summary of Contents for 2000 Series
Page 1: ...2000 Series Troubleshooting Guide P N 83 00004287 12 Revision A May 2008 ...
Page 18: ...18 R Evolution 2000 Series Troubleshooting Guide May 2008 ...
Page 34: ...34 R Evolution 2000 Series Troubleshooting Guide May 2008 ...
Page 64: ...64 R Evolution 2000 Series Troubleshooting Guide May 2008 ...
Page 78: ...78 R Evolution 2000 Series Troubleshooting Guide May 2008 ...