IBM DS4700 manual Cache memory and cache battery

CAUTION:

The power switch on the power supply and fan unit does not turn off the electrical current supplied to the device. The DS4700 Express Storage Subsystem might also have more than one connection to dc power. To remove all electrical current from the device, ensure that all dc power cords are disconnected from the power supply and fan unit dc input connectors.

While the storage expansion enclosure powers up, the LEDs on the front and the back of the module blink intermittently. Depending on your configuration, the storage expansion enclosure can take between 20 seconds and several minutes to power on.

9.Turn on both power switches on the back of the storage subsystem.

A storage subsystem can take 10 seconds to power on and up to 15 minutes for the battery self-test to complete. During this time, the LEDs on the front and the back of the modules blink intermittently.

10.Check the status LEDs on the front and back of the storage subsystem.

a.Note the status of the LEDs on the front and back of each module.

A green LED indicates a normal status; amber LEDs indicate a hardware fault.

b.Open the Subsystem Management window for the storage array.

c.Select the appropriate components button for each module in the Physical View of the Subsystem Management window to view the status of its components.

The status for each component is either Optimal or Needs Attention.

11.Does each module display green LEDs only, and is the status Optimal for each module component?

v Yes - Go to step 13.

vNo - Go to step 12.

12.Diagnose and correct the fault.

a.To run the Recovery Guru, select the Recovery Guru toolbar button in the Subsystem Management window.

b.Complete the recovery procedure.

If the Recovery Guru directs you to replace a failed component, locate and troubleshoot that component. See “Checking the LEDs” on page 125.

c.When the procedure is completed, rerun the Recovery Guru to ensure that the problem has been corrected by selecting Recheck in the Recovery Guru.

d.If the problem persists, contact IBM Customer and Technical Support.

13.Replace the bezel on the storage expansion enclosure, if applicable.

Cache memory and cache battery

Each RAID controller in the DS4700 Express Storage Subsystem contains either 1 GB or 2 GB of cache memory to store read and write operations. (Both RAID controllers in the DS4700 Express must have the same amount of cache memory.) The battery unit in each controller can maintain the data in the RAID controller caches for up to three days in the event that the DS4700 Express Storage Subsystem loses power.

140IBM System Storage DS4700 Express Storage Subsystem: Installation, User’s and Maintenance Guide