Monitoring and Tuning Your Server
Monitoring and Tuning Your Server |
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There are several counters in the Memory and Cache performance objects that you can use to monitor the size and effectiveness of the File System Cache. Table 5.3 lists these counters.
Table 5.3 Counters for Monitoring the File System Cache
| Counter | Indicates |
| Memory\ Cache bytes | The size of the cache, in bytes. This counter displays the last observed value; it is not an average. |
| Memory\ Cache faults/sec | How often data sought in the File System Cache is not found there. The count includes faults for data found elsewhere in memory, as well as faults that require disk operations to retrieve the requested data.
This counter displays the number of faults, regardless of the number of pages retrieved in response to the fault. |
| Cache\ Copy Reads/sec | The frequency of reads from pages of the File System Cache that involve a memory copy of the data from the cache to the application’s buffer. This is a method used by the LAN Redirector, the LAN Server (for small items), and the disk file systems. |
| Cache\ Fast Reads/sec | The frequency of reads from the File System Cache that bypass the installed file system and retrieve the data directly from the cache. Normally, file I/O requests invoke the appropriate file system to retrieve data from a file. However, this path permits direct retrieval of data from the cache without file system involvement, if the data is in the cache. Even if the data is not in the cache, one invocation of the file system is avoided. |
| Cache\ MDL Reads/sec | How often the system attempts to read large blocks of data from the cache.
Memory Descriptor List (MDL) Reads are read operations in which the system uses a list of the physical address of each page to help it find the page. MDL Reads are often used to retrieve cached Web pages and FTP files. |
| Cache\ Pin Reads/sec | How often the system attempts to read recently accessed blocks of data from the cache. This counter is more accurate for ASP content than the MDL Reads/sec counter is.
Pin counters display reads of cache data that is held because it has just been read or written. They reflect cache data that is used repeatedly. |
| Cache\ MDL Read Hits % | How often attempts to find large sections of data in the cache are successful.
You can use the Cache\ MDL Read Hits % counter to calculate the percentage of MDL misses. Misses are likely to result in disk I/O. |
| Cache\ Pin Read Hits % | How often attempts to find recently accessed sections of data in the cache are successful. This counter is more accurate for ASP content than the MDL Read Hits % counter is.
You can use the Cache\ Pin Read Hits % counter to calculate the percentage of misses. Misses are likely to result in disk I/O. Pin counters display reads of cache data that is held because it has just been read or written. They reflect cache data that is used repeatedly. |
| Cache\ Data Maps/sec | How often pages are mapped into the cache from elsewhere in physical memory or from disk.
To measure the percentage of data maps from elsewhere in physical memory, use Cache\ Data Map Hits %. 100 minus the value of Cache\ Data Map Hits % is the percentage of data maps retrieved from disk. |
| Cache\ Read Aheads/sec | A measure of sequential reading from the cache. When the system detects sequential reading, it anticipates future reads and reads larger blocks of data. The read ahead counters are a useful measure of how effectively an application uses the cache. |
| Memory\ Page Faults/sec | Hard and soft faults in the working set of the process. This counter displays the number of faults, without regard for the number of pages retrieved in response to the fault. |
| Memory\ Page Reads/sec | Hard faults in the working sets of processes and in the File System Cache. |
Note You should log this data over several days, because cache behavior varies over time.