“\Memory\Page faults/sec” is the rate at which the processor handles both soft and hard faults. “\Memory\Page Reads/sec” and “\Memory\Page Writes/sec” show how much the disk is affected by paging operations based on the rate that pages that are read and written to the disk. Pages Input/sec is the total number of pages read from the disk, and Pages Output/sec is the total number of pages sent to disk from memory. “\Memory\Pages/sec” is the sum of “\Memory\Pages Input/sec” and “\Memory\Pages Output/sec”. Green= Page Reads/sec Pink= Pages Input/sec Conclusion A large quantity of hard page faults could signify that you need to increase the amount of memory or reduce the cache size on the server. Pages Input/sec will be greater than or equal to Page Reads/sec if you have hard faults (see below). To discover whether or not you’re experiencing hard page faults, compare your values of Pages Input/sec and Page Reads/sec to determine the average number of pages read into memory during every operation. If your Pages Input/sec counter shows a value of 20 or greater for a slow disk and/or your Pages/sec counter consistently shows more than 40 pages per second on a slow disk or 300 per second on a fast disk, you can solve this issue simply by adding more memory to your server. Red= Page Faults/sec Green= Pages/sec Troubleshooting If my Page reads/sec were also high, that would be a strong indicator of insufficient RAM. As you can see, my rate of page faults is skyrocketing. The “\Memory\Page faults/sec” counter, shown below, monitors the rate at which the processor handles both soft and hard faults. Most processors can manage soft faults, but hard faults can instigate substantial delays. On the other hand, if the page must be retrieved from the disk, this is a hard fault. If the requested page is still in memory but perhaps in the wrong process, this is a soft fault. The page fault is placed in a “wait” state while the operating system attempts to restore that page to physical memory. A page fault results when a process requests a page in memory, but the system can’t recover it from the requested location. Page faults are one of the most common memory-related bottleneck issues encountered with paging operations that can be monitored by Pages/sec and its associated memory counters. Your system memory is-in all likelihood-too small for the processing load. If your Pages/sec counter consistently shows more than 40 pages per second on a slow disk or 300 pages per second on a fast disk, you should investigate. A faster disk should be able to process more. However, if your Pages Input/sec counter shows a value of 20 or greater for a slow disk, you should closely monitor it. Even if they spike occasionally, you have no cause for concern if they soon return to the same values (or approximations). The lower the memory system’s paging values, the better. Thus, you should rule out memory problems accordingly before examining other system areas for potential sources. Memory is frequently the root cause of performance problems. Green= Page Reads/sec Yellow= Page Writes/sec Potential Problems Page Writes/sec is the rate at which page data is written to the disk to open up space in physical memory. Page Reads/sec is the rate at which the disk is read to resolve page faults. Pink= Pages Input/sec Blue= Pages Output/secĬlosely related to Pages/sec are the “\Memory\Page Reads/sec” and “\Memory\Page Writes/sec” counters, as they show how much the disk is affected by paging operations. My Pages Output/sec is so low that it doesn’t show on the graph below, being flatlined. Pages Input/sec is the total number of pages read from the disk, and Pages Output/sec represents the total number of pages removed from memory and traveling toward the disk. “\Memory\Pages/sec” is based on the combined input and output of pages, also referred to as the “\Memory\Pages Input/sec” and “\Memory\Pages Output/sec” counters. Disk Queue Length represent in the queue to pinpoint possible bottleneck, you should also keep an eye on the Pages Per Second counter to determine whether you are at risk of the memory system becoming limited or diminished. Just as you should monitor the number of requests that Current and Avg. Continuing with last week’s article on Current and Average Disk Queue Length, this week we’ll discuss Pages Per Second and its related counters.
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