Ds4300 Storage Server Cache Active Led - IBM TotalStorage DS4000 Hardware Maintenance Manual

See the storage management software documentation for information on how to set
cache memory options.
The RAID controller has a Cache active LED that displays the current status of the
cache. The LED is on if data is in the cache, and it is off if no data is in the cache.
If caching is enabled and the Cache active LED never comes on during I/O
activity, it indicates that the cache memory failed or the battery failed (the green
Battery LED will be off).
Note: Always use the storage management software to check your cache memory
settings before you assume a hardware failure. On the DS4300
single-controller storage server (model 6LU/6LX), the RAID controller cache
memory is used for storing read data only. The controller firmware ignores a
"write-cache enabled" setting. This protects data in the event of a controller
failure, which would cause the cache to be inaccessible.
Figure 53 shows the location of the Cache active LED on the front of the RAID
controller.
Figure 53. DS4300 storage server cache active LED
RAID controller cache battery
Each RAID controller contains a sealed, rechargeable 4-volt lead-acid battery. This
battery provides cache backup for up to three days in the event of a power loss.
The service life of the battery is three years, after which time the battery must be
replaced. See the storage management software for information on how to view
and set the battery expiration date.
Important: The replacement RAID controller CRU does not come with a RAID
controller cache battery installed, nor the mounting hardware that holds the
battery in place inside the RAID controller. You must remove the cache battery that
is inside the existing RAID controller that you are replacing, and install that
battery inside the replacement RAID controller CRU, using the battery unit
mounting hardware taken from the existing controller. On the DS4300 model
6LU/6LX, you will have to stop all I/O to the storage server before you replace
the battery. The steps to remove and replace the battery are included in the IBM
TotalStorage DS4300 Storage Server Installation and User's Guide.
Each RAID controller has a green Battery LED on the back that indicates the
following battery statuses:
v The LED is on and remains steady when the battery is fully charged.
Cache
active
LED
Chapter 9. Type 1722 DS4300 Storage Server
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