Attention: To avoid potential data loss, ensure that the storage subsystem
and storage enclosure power switches are turned off before you reset circuit
breakers in the rack. Resetting circuit breakers after an emergency situation
while the storage subsystem and storage enclosure power switches are
turned on can cause data loss, because the configuration components might
not be powered-on in the correct sequence. See “Turning on the storage
subsystem” on page 82 for details about the correct power-on sequence.
2. After you check the storage subsystem for damage, ensure that the power
switches are off; then connect the DS3500 power cables, if required.
3. Check the system documentation of the hardware devices that you want to
turn on and determine the correct startup sequence.
Be sure to turn on all of the storage enclosures and make sure that no ESM or
power-supply fault LEDs are lit before you turn on the storage subsystem.
In addition, consider the following items:
v The storage subsystem supports simultaneous power-on of the system
components; however, always check the system documentation of the
hardware devices that you want to turn on and determine the correct startup
sequence.
v A storage subsystem in an optimal state recovers automatically from an
unexpected shutdown and unattended simultaneous restoration of power to
system components. After power is restored, contact your IBM
technical-support representative if any of the following conditions occur:
– The storage subsystem logical drives and subsystems are not displayed in
the Storage Manager graphical user interface.
– The storage subsystem logical drives and subsystems do not come online.
– The storage subsystem logical drives and subsystems seem to be
degraded.
4. Turn on the power to each device, according to the startup sequence.
5. If there are enclosures with dc power supplies in your storage subsystem, turn
on the -48V disconnect devices before turning on the power-supply switches.
6. Turn on both of the power-supply switches on the DS3500. The green LEDs on
the front and the rear of the DS3500 should remain lit. If other amber LEDs are
lit, see Chapter 6, “Solving problems,” on page 161.
Recovering from an overheated power supply
Each storage subsystem contains two power supplies. Each power supply contains
a built-in temperature sensor to prevent the power supply from overheating.
Under normal operating conditions, with an ambient air temperature range of 10°C
to 40°C (50°F to 104°F), the fans in the power supplies maintain a suitable
operating temperature inside the module.
If the internal temperature reaches 65°C (149°F), the power supply shuts down
automatically. If both power supplies shut down because of overheating, the
storage subsystem has no power, and all LEDs are off.
The following factors can cause the power supplies to overheat:
v An unusually high room temperature
v Fan failures in the power supplies
v Defective circuitry in a power supply
v Blocked air vents
v Failures in other devices in the configuration or rack
Chapter 4. Operating the storage subsystem and storage enclosure 99
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