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It is recommended to use character devices to test product performance according to customers' test environment.

Publication Date:  2012-07-18 Views:  13 Downloads:  0
Issue Description
A customer consulted whether one of the 1+1 redundant power supplies in the S5000 can be powered down?
Alarm Information
None
Handling Process
When both power modules of the S5000 are working properly and either of the power supplies can provide sufficient power to the S5000 under rated voltage and current, the S5000 can continue to work correctly after a power supply is powered down. Before that, you must understand the cache write policy variation mentioned in "Possible causes".
Root Cause
The two power supplies of the S5000 are designed in 1+1 redundant mode. Either of the power supplies can provide sufficient power to the S5000 under standard voltage and current. In the conditions where only one power supply is used to power the S5000, the cache write policy is automatically changed from write back to write through for directly writing cache data to disks when a power failure occurs. This mechanism improves data storage security. Given the write through policy directly writes data to disks without using the cache, the storage performance can be degraded. When both power supplies are used, the cache write policy is changed from write through to write back.
Suggestions
To protect the storage device and running services, you are advised to use both power supplies to power the S5000.

END