NEC Storage S1300 User Manual page 71

The disk array unit periodically writes data from the cache memory onto a disk drive.
If you turn off the AC power before completion of write to the disk drive, the remaining
data in the cache memory is backed up by the battery backup units (the Battery LED on
the controller is lit).
However, the backup time is limited (3 days if the two battery backup units are fully
charged). To securely protect data, write all the data remaining in cache memory in the
disk array unit onto the disk drive according to the following procedure. Then turn off
the AC power according to the procedure described on previous page.
1. Turn off the host system. Alternatively, offline all the buses connected to the host
system that is connected to the disk array unit.
2. Press and hold the shut down switch (push-switch with SDN indicated) of the LAN
card installed in the disk array unit for several seconds until the SDN LED starts to
flash or go on. Release the switch when the SDN LED starts to flash or go on.
Note
: While the shut down switch is on, the disk array unit
does not accept any I/O operation by the host system. When the disk
array unit restarts, the disk array unit normally accepts I/O operations
by the host system.
3. Confirm that the SDN LED of the LAN card installed in the disk array unit stops
flashing and goes on, and then turn off the AC power according to the procedure
described on previous page.
4. The SDN LED flashes while data remaining in cache memory is being written onto
the disk drive. Do not turn off the AC power while it is flashing.
Notes
:
If you turn off the AC power of the disk array unit during write
operation (with the SDN LED flashing) by mistake, the backup
mode is enabled. (In this case, the controller's battery LED goes
on.)
If you turn off the AC power of the disk array unit during write
operation (with the SDN LED flashing) by mistake, turn on the
AC power of the entire disk array unit again. When the disk array
unit has started (when the READY LED of the controller on the
disk array unit stops flashing and enters the ON state), press and
hold the shut down switch for several seconds until the SDN LED
starts to flash or go on to complete the write operation.
Relationship between SDN LED states and operations of the disk array unit is as
follows:
Normal state
During cache data write
onto disk drive
Completion of cache data
write onto disk drive
Off
Flashing (On for 500 ms,
Off for 250 ms)
On
Setting Up the System 2-23