User Guide
76 Spheras Storage Director Installation and User Guide
3 Select Basic.
Figure 50 Figure 50 Controller Properties Dialog Box: Basic
In the Basic tab, you have the following options:
Enable read ahead: When enabled, reads data to the next stripe boundary (based on stripe size), and
retains in cache any data beyond the size of the actual read request.
The Read Ahead function improves data retrieval performance by allowing the
controller to read into cache a full stripe of data at a time. This greatly improves the
percentage of cache hits. For small transfers, the read ahead algorithm helps with
performance.
For example, if the stripe size is set to 8 KB and the host requests 1 KB of data,
when this function is enabled the controller reads the full 8 KB. When the host
requests the next 1 KB block, that data is already in the controller’s cache. This