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Low Read Performance When Reading and Writing Large Files on LUNs Due to LUN Property Errors

Publication Date:  2013-05-09 Views:  97 Downloads:  7
Issue Description
The read performance is low when reading and writing two large files on the same LUN, and the remaining time of read file copy keeps growing or is invisible on the application server.
Product and version information:
  • S2600
  • S5000 series
Alarm Information
None
Handling Process
Step 1 Wait until the background formatting of the LUN is complete.
Log in to the ISM and unfold the storage device. Choose Storage Resources > LUNs. In the right function pane, view the property of the faulty LUN. If the Running Status is Online, the formatting is complete.
Step 2 Set the write policy of the LUN to write back.
In the right function pane, select the LUN that you want to modify and click Modify. In the Modify LUN dialog box that is displayed, set the write policy.
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Root Cause
1. In the navigation tree of the ISM, unfold the storage device. Choose Storage Resources > LUNs. In the right function pane, view the property of the faulty LUN.
2. The LUN is either running background formatting, or the write policy of the LUN has been set to write through.
Therefore, we have the following conclusion:
The LUN is either running background formatting or its write policy has been set incorrectly, causing low read performance when reading and writing large files concurrently on the LUN.
Suggestions
Take measures as suggested below to avoid this problem:
  • Make sure that the background formatting has been completed for the LUN before reading and writing large files concurrently.
  • Set the write policy of the LUN to write back.
The processing performance of storage devices may be deteriorated when the background formatting is ongoing or the write policy is set to write through.

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