Cache Memory And Raid Controller Battery; Cache Memory - IBM TotalStorage DS4300 Installation And User Manual

Cache memory and RAID controller battery

Each RAID controller in the DS4300 standard storage server contains 128 MB of
cache memory. Each controller in the DS4300 Turbo storage server contains 896
MB of cache memory.
Each controller also contains a rechargeable battery that maintains data in the
cache for up to three days in the event of a power failure. The following sections
describe these features and their associated LEDs.

Cache memory

Cache memory is memory that is used for intermediate storage of read and write
data on the DS4300 dual-controller storage server's RAID controllers (Model
60U/60X). Using cache memory can increase system performance. The data for a
read operation from the host might be in the cache memory from a previous
operation (thus eliminating the need to access the drive itself), and a write operation
is completed when data is written to the cache, rather than to the drives.
Note: On the DS4300 single-controller storage server (Model 6LU/6LX), the RAID
See the storage-management software documentation for information on setting
cache memory options.
The RAID controller has a Cache active LED that displays the current status of the
cache. The LED is on if there is data in the cache, and it is off if there is no data in
the cache.
Table 13. Fan LED
LED Color
Fault Amber
1
Always use the storage-management software to identify the failure.
Table 14. Power supply LEDs
LED Color
Fault Amber
Power Green
1
Always use the storage-management software to identify the failure.
controller's 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.
1
Operating states
v Off - Normal operation.
v On - The fan CRU has failed.
1
Operating states
v Off - Normal operation.
v On - One of the following situations has occurred:
– The power supply has failed.
– An over-temperature condition has occurred.
v On - Normal operation.
v Off - One of the following situations has occurred:
– The power supply is disconnected.
– The power supply is seated incorrectly.
– The storage server has no power.
– The power supply is turned off.
Chapter 4. Operating the storage server
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