Dell IP4700 Installation And Service Manual page 58

Installing an IP4700
2
for the light to go off and the fans to stop before proceeding with
further service to the storage system.
CAUTION
!
Never remove the fan pack and shut off the power supply to shut
down an IP4700. Doing so effectively bypasses the SPS, and write
cache data cannot be saved to the vault drives, which results in data
loss. When that happens, volumes become inaccessible and the
unsolicited event log displays an error message similar to:
"Enclosure 0 Disk 5 0x90a (Can't Assign - Cache
Dirty) 0 0xafb40 0x14362c."
Contact your service provider if this situation occurs.
IP4700 Installation and Service Guide
2-22