This release brings a new cache counter, Cache: Read Aheads/sec and a redefinition of some original counters. For more information, see Chapter 15, "Detecting Cache Bottlenecks."
The Cache hit counters have been changed: They now measure the percentage of hits, regardless of the number of pages found. This better reflects the costs and benefits of cache hits and misses. The frequency of hits is much more important than the size of the hit.
The affected counters are:
For more information, select each of these counters from the Add to Chart dialog box and click the Explain button.
Cache: Read Aheads/sec is a new Performance Monitor counter that counts read aheads in each second and averages the values over the last two timed intervals. A read ahead occurs when the Cache Manager detects that a file is read sequentially and moves larger blocks of sequential data into the cache. Read aheads are more efficient because more data is moved in each disk operation and fewer disk operations are required