Windows Memory Performance (NT_MEMORY)
Attributes (parameters)
The following attributes are available for this monitor type:
Name | Description | Unit | Default Performance Key Indicator (KPI) |
---|---|---|---|
Available bytes (MEMmemAvailableBytes) | Displays the number of megabytes of physical memory currently available to processes, but is not related to the amount of physical memory installed in your server. The value of this parameter is calculated by adding the space on the Zeroed, Free, and Standby memory lists. Zeroed memory is filled with zeros to prevent later processes from seeing data used by a previous process. Free memory is ready for use by any process. Standby memory has been removed from a process's working set on route to disk but is still available for recall. Recommendations The value for this parameter should never drop to less than 4 MB, even during peak usage times, and should be 10 MB or more:
Thresholds for alarms and warnings You should set appropriate Alarm and Warning values for your system based on the Baselining Overview topic. | MB | Yes |
Cache bytes (MEMmemCacheBytes) | Displays the number of megabytes currently in use by the system cache. The system cache is used to buffer data retrieved from disk or LAN. The system cache uses memory not in use by active processes in the computer. | MB | No |
Cache faults (MEMmemCacheFaultsPerSec) | Displays the frequency of cache faults. Cache faults occur whenever the cache manager does not find a file's page in the immediate cache. Recommendations The ratio of hard page faults to total page faults (that is, MEMmemPagesInputPerSec/MEMmemPageFaultsPerSec) should not be greater than about 0.05 to 0.10. If the ratio goes higher than this value, the system is spending too much time on paging activity, and you should consider installing additional memory resources.
If MEMmemPagesPerSec is greater than 10 (10 is a reasonable number, but may vary with disk hardware) and MEMmemPageFaultsPerSec is greater than MEMmemCacheFaultsPerSec, the system is paging too much and you should install additional memory. Thresholds for alarms and warnings No default thresholds have been set for this parameter. The Baselining Overview topic may help you determine appropriate settings for your system. | per sec | No |
Commit limit (MEMmemCommitLimit) | Displays the amount of virtual memory that can be committed without having to extend the paging file(s). Committed memory is the physical memory that is being used. The space for committed memory is reserved in the paging file. There can be one paging file on each logical drive. If the size of the paging file increases, this limit increases accordingly. | MB | No |
Committed bytes in use (MEMmemCommittedBytesPercent) | Displays the ratio of memory/committed bytes to memory/commit limit. Committed memory is the physical memory that is being used. The space for committed memory is reserved in the paging file. The commit limit is determined by the size of the paging file. If the size of the paging file increases, the commit limit also increases, and the ratio reduces. | % | No |
MEMMemoryColl | Collects memory statistics from the memory performance objects in the Windows Performance Database. | Not applicable | No |
Page faults (MEMmemPageFaultsPerSec) | Displays the number of hard and soft page faults in the processor. Page Faults are normal for processors and do not necessarily imply a performance bottleneck. There are two kinds of page faults:
A soft page fault can be resolved without accessing a disk drive. A hard page fault must be resolved by physically accessing a disk drive. Recommendations Add memory if:
Alternatives to adding memory:
You can use composite parameters to monitor the relationship between MEMmemPagesPerSec, MEMmemPageFaultsPerSec and MEMmemCacheFaultsPerSec. Thresholds for alarms and warnings You should set appropriate Alarm and Warning values for your system based on the Baselining Overview topic. | per sec | No |
Pages input (MEMmemPagesInputPerSec) | Displays the number of pages read from the disk to resolve memory references to pages that were not in memory at the time of the reference. This parameter also includes paging activity incurred by the system cache accessing file data for applications. This activity is referred to as hard page faults. Recommendations The ratio of hard page faults to total page faults (that is, MEMmemPagesInputPerSec), should not be greater than about 0.05 to 0.10. If the ratio goes higher than this value, the system is spending too much time on paging activity. You should consider installing additional memory resources.
Note You can use composite parameters to monitor the relationship between MEMmemPagesPerSec, MEMmemPageFaultsPerSec and MEMmemCacheFaultsPerSec. For more information, see the Using Composite Parameters topic. Thresholds for alarms and warnings No default thresholds have been set for this parameter. The Baselining Overview topic may help you determine appropriate settings for your system. | per sec | No |
Pages output (MEMmemPagesOutputPerSec) | Displays a count of the number of pages written to disk because the pages have been modified in main memory. | per sec | No |
Pages (MEMmemPagesPerSec) | Displays the number of hard page faults for the processor, and the value often determines whether or not your system needs more RAM. The number of hard page faults is equal to the number of pages read from, or written to, disk to resolve memory references to pages that were not in memory at the time of the reference. The parameter's value is the sum of the MEMmemPagesInputPerSec and MEMmemPagesOutputPerSec parameters. Recommendations
Thresholds for alarms and warnings You should set appropriate Alarm and Warning values for your system based on the Baselining Overview topic. | per sec | No |
Memory active (MEMmemVMActive) | Displays the estimated amount of memory the virtual machine is actively using. This parameter appears only when the "VM Memory" performance counters are available on the virtual machine. | MB | No |
Memory ballooned (MEMmemVMBallooned) | Displays the amount of memory that has been reclaimed from a virtual machine through the VMware memory balloon mechanism. | MB | No |
Memory limit (MEMmemVMLimit) | Displays the maximum amount of memory that is allowed to a virtual machine. Assigning a memory limit ensures that this virtual machine never consumes more than a certain amount of the allowed memory. By limiting the amount of memory consumed, a portion of this shared resource is allowed to other virtual machines. | GB | No |
Memory mapped (MEMmemVMMapped) | Displays the mapped memory size of a virtual machine. This is the current total amount of guest memory that is backed by physical memory. | MB | No |
Memory overhead (MEMmemVMOverhead) | Displays the amount of overhead memory associated with a virtual machine that is consumed on the host computer. | MB | No |
Memory reservation (MEMmemVMReservation) | Displays the minimum amount of memory that is guaranteed to a virtual machine. Assigning a memory reservation ensures that even as other virtual machines on the same host consume memory, there is still a certain minimum amount for this virtual machine. | MB | No |
Memory shared (MEMmemVMShared) | Displays the amount of physical memory associated with a virtual machine that is copy-on-write (COW) shared on the host. | MB | No |
Memory shared saved (MEMmemVMSharedSaved) | Displays the estimated amount of physical memory on the host saved from copy-on-write (COW) shared guest physical memory. | MB | No |
Memory swapped (MEMmemVMSwapped) | Displays the amount of memory associated with a virtual machine that has been swapped by ESX. | MB | No |
Memory used (MEMmemVMUsed) | Displays the estimated amount of physical host memory currently consumed for a virtual machine's physical memory. This memory is calculated as follows: | MB | No |
System cache resident bytes (MEMmemSystemCacheResidentBytes) | Size of the pageable operating system code in the file system cache. This value includes only current physical pages and does not include any virtual memory pages not currently resident. | MB | No |
Total kernel memory (MEMmemTotalKernelMemory) | The total of paged and nonpaged memory pool bytes. | MB | No |