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To protect the storage device and running services, you are advised to use both power supplies to power the S5000.

Publication Date:  2012-07-18 Views:  80 Downloads:  0
Issue Description
At a commercial deployment, the cache write policy of the LUNs on the S5000 is configured as write back on the management Web page. However, the write performance degrades when a power supply, battery, or fan becomes faulty. Alarm information: Alarm messages stating a power supply, battery, or fan is faulty or cannot be detected are displayed.
Alarm Information
none
Handling Process
Recover or replace the faulty module.
Root Cause
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 data to disks when a power failure occurs. This mechanism improves data storage security. For redundant power supplies, fans and batteries, the S5000 is designed to automatically change the cache write policy from write back to write through when a power supply, fan, or battery becomes faulty. Given the write through policy directly writes data to disks without using the cache, the storage performance can be degraded. After the faulty power supply, fan, or battery is recovered, the cache write policy is automatically changed from write through to write back. Note that the LUN write policy always displays as the preset write back status on the Web page even after it is changed to write through for some reason.
Suggestions
Recover or replace the faulty power supply, fan, or battery in time

END