Hitachi AMS 2100 Hardware Manual page 215

configuration
The number of RAID Groups can be expanded in the AMS2000 series. To
realize this scalability, it is designed to keep average throughput even when
the multiplicity of I/O is high. However, you can improve the I/O response
time using the Cache preferentially in cases where the number of RAID
Groups is small — about one to three in the configuration — and the Write
I/O load is low, or the load only grows momentarily.
By setting this option, the write data is stored as much as possible in the
Cache, and it changes to the operation that suppresses the I/O issue to the
drive. The collision of the host I/O and drive I/O may be reduced by
suppressing the I/O issue to the drive, so that you may improve the Write
I/O response time.
However, in the case of continuously writing the data volume greatly
exceeding the cache memory size, the throughput may temporarily
deteriorate. Therefore, you need to be careful when setting the option.
Hitachi Data Systems recommends you set this option with your specific
environmental conditions in mind.
The setting procedure is described below.
1. Select the array from the Hitachi Storage Navigator Modular 2, and then
select the Tuning Parameter icon in the Performance tree. The Tuning
Parameter window is displayed.
2. Click the Change Simple Tuning button.
•
3. The Change Simple Tuning window is displayed. Turn ON the Response
Performance Mode to improve the I/O response time.
Hitachi AMS 2100/2300 Storage System Hardware Guide
Configuration
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