Performance Monitor Objects
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4620-1 appA.f.qc 10/28/99 12:34 PM Page 751 Appendix A Performance Monitor Objects s discussed in Chapter 18, this appendix provides you with selected A Performance Monitor object:counter definitions. I’ve only provided the core object:counters here, in the interest of time and space, but also according to their importance. To be honest, most of the object:counters I have omitted are not used by Windows 2000 Server administrators and engineers. What I’ve attempted to do is only list the definitions and explanations for the object:counters you are likely to use in the management of your Windows 2000 Server network. However, exceptions and additions exist. The objects for which counters are defined in this appendix include the following: I Cache I Logical Disk I Memory I Network Interface I Network Segment I Objects I Physical Disk I Process I Processor I Redirector I Server Work Queues I System I Thread Third-party ISVs have long taken advantage of Performance Monitor in several ways. First, during the software application development cycle, ISVs use Performance Monitor to monitor the health and performance of the Windows 2000 Server machine and network. This not only enables them to see that their development environment is either running optimally or similar to that of their customers, but it also enables them to see how their software applications are impacting the system. Second, the ISVs typically write object:counters that are unique to their software application, which they run as part of Performance Monitor. Here again, this enables them to monitor and 4620-1 appA.f.qc 10/28/99 12:34 PM Page 752 752 Appendixes I I optimize their software application during the development cycle. But perhaps most important, by creating application-specific object:counters, ISVs expose a wealth of monitoring and optimization possibilities for you, the customer. For example, when you purchase and install Microsoft SQL Server, several object:counters specific to this application are added to Performance Monitor. When using and developing with SQL Server, you benefit greatly from these SQL Server-specific object:counters in the management of your database applications and your network. For descriptions of object:counters not listed here, simply click the explain button for the object:counter of your choice in the Add Counters dialog box. Table A-1 Performance Monitor Object Types Object Object Counter Description Cache Async Copy Reads/sec Measures the frequency of reads from cache pages involving a memory copy of the data from the cache to the application’s buffer. Application regains control immediately even if the disk must be accessed to retrieve the page. Cache Async Data Maps/sec Measures the frequency at which an application, using a file system such as NTFS to map a page of a file into the cache, reads the page and does not wait for the cache to retrieve the page if not found in main memory. Cache Async Fast Reads/sec Measures the frequency of reads from cache pages that bypass the installed file system and retrieve the data directly from the cache. Typically, the file I/O requests invoke the appropriate file system to retrieve data from a file, but this path permits direct retrieval of cache data 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. If the data is not in the cache, the request (application program call) does not wait until the data is retrieved from disk, but gets control immediately. 4620-1 appA.f.qc 10/28/99 12:34 PM Page 753 Appendix A: Performance Monitor Objects 753 I I Object Object Counter Description Cache Async MDL Reads/sec Measures the frequency of reads from cache pages using a Memory Descriptor List (MDL) to access the pages. Note that the MDL contains the physical address of each page in the transfer, thus permitting direct memory access (DMA) of the pages. If the accessed page(s) are not found in main memory, the calling application program does not wait for the pages to fault in from disk. Cache Async Pin Reads/sec This measures the frequency of reading data into the cache preparatory to writing the data back to disk. Pages read in this fashion are pinned in memory at the completion of the read. File system regains control immediately even if the disk must be accessed to retrieve the page. A page’s physical address is not altered while pinned. Cache Copy Read Hits % Displays the percentage of cache Copy Read requests that hit the cache. Stated another way, does not require a disk read in order to provide access to the page in the cache. Copy Read is a file read operation that is satisfied by a memory copy from a cache page to the application’s buffer. The LAN redirector and disk file systems use this method for retrieving cache information, as does the LAN server for small transfers. Cache Copy Reads/sec Measures the frequency of reads from cache pages that involve a memory copy of the data from the cache to the application’s buffer. The LAN redirector uses this method for retrieving cache information, as does the LAN server for small transfers. Cache Data Flush Pages/sec Measures the frequency of the number of pages that the cache flushes to disk as a result of a request to flush or to satisfy a write-through file write request. More than one page can be transferred on each flush operation. Continued 4620-1 appA.f.qc 10/28/99 12:34 PM Page 754 754 Appendixes I I Table A-1 (continued) Object Object Counter Description Cache Data Flushes/sec This is the frequency that the cache flushes its contents to disk as the result of a request to flush or to satisfy a write-through file write request. One page or more can be transferred on each flush operation. Cache Data Map Hits % This is the percentage of data maps in the cache that can be resolved without having to retrieve a page from the disk — in other words, the page is already in physical memory. Cache Data Map Pins/sec This is the frequency of data maps in the cache that results in pinning a page in main memory, an action usually preparatory to writing to the file on disk. A page’s physical address in main memory and virtual address in the cache are not altered while pinned. Cache Data Maps/sec This is the frequency at which a file system such as NTFS maps a file page into the cache to read the page. Cache Fast Read Not This is the frequency of attempts by an Possible/sec Application Program Interface (API) function call to bypass the file system to get at cache data that cannot be honored without invoking the file system. Cache Fast Read Resource This is the frequency of cache misses Misses/sec necessitated by the lack of available resources to satisfy the request. Cache Fast Reads/sec This is the frequency of reads from cache pages that bypass the installed file system and retrieve the data directly from the cache. Typically, file I/O requests invoke the appropriate file system to retrieve data from a file, but this path permits direct retrieval of cache data without file system involvement if the data is in the cache. 4620-1 appA.f.qc 10/28/99 12:34 PM Page 755 Appendix A: Performance Monitor Objects 755 I I Object Object Counter Description Cache Lazy Write Flushes/sec Lazy writing is the process of updating the disk after the page is changed in memory, so that the application making the change to the file does not have to wait for the disk write to complete before proceeding. It is possible for more than one page to be transferred on each write operation. Cache Lazy Write Pages/sec This is the frequency with which the cache’s lazy write thread is written to disk. Lazy writing is the process of updating the disk after the page is changed in memory, so that the application making the change to the file does not have to wait for the disk write to complete before proceeding. It is possible for more than one page to be transferred on a single disk write operation. Cache MDL Read Hits % This is the percentage of cache memory descriptor list (MDL) read requests that have hit the cache — that is, that do not require disk accesses in order to provide memory access to the page(s) in the cache. Cache MDL Reads/sec This is the frequency of reads from cache pages that use a memory descriptor list (MDL) to access the data. The MDL contains the physical address of each page involved in the transfer and thus can employ a hardware direct memory access (DMA) device to effect the copy. Note that a LAN server uses this method for large transfers out of the server. Cache Pin Read Hits % This is the percentage of cache Pin Read requests that have hit the cache, that is, that do not require a disk read in order to provide access to the page in the cache. A page’s physical address in the cache is not altered while pinned. Note that a LAN redirector uses this method for retrieving cache information, as does the LAN server for small transfers and disk file systems. Continued 4620-1 appA.f.qc 10/28/99 12:34 PM Page 756 756 Appendixes I I Table A-1 (continued) Object Object Counter Description Cache Pin Reads/sec This is the frequency of reading data into the cache preparatory to writing the data back to disk.