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Why the Write Performance of LUNs Is Low If no BBU or UPS Is Configured?

Publication Date:  2012-07-22 Views:  82 Downloads:  0
Issue Description
On a deployment site, two file folders stored on the same LUN replicate each other at a speed of only 10 MB per second. The write performance to a LUN is low. However, the network adapter is a GE adapter, and all hardware components are of high performance.  
Alarm Information
Handling Process
Change the LUN write policy from Write Back to Write Back Mandatory manually.
Root Cause
Log in to the management interface of the storage system to view the LUN write policy and find that the set policy is Write Back while the actual policy is Write Through. This conflict deteriorates the write performance of LUNs.
1. The only solution is to change the write policy to Write Back Mandatory.
2. Check whether the storage device is configured with BBUs or UPSs. The change of LUN write policy from Write Back to Write Through is usually caused by the absence of power protection mechanism.
3. Customers are advised to configure UPSs or BBUs for their storage systems; otherwise, dirty data in cache is lost upon an unexpected power failure.