Memory Details Test

This test reports statistics pertaining to the memory utilization of target systems.

This test reports statistics pertaining to the memory utilization of target systems. The measures made by this test are as follows:

Target of the test : Any host system

Agent deploying the test : An internal agent

Outputs of the test : One set of results for every server being monitored

  1. TEST PERIOD - How often should the test be executed
  2. Host - The host for which the test is to be configured
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Free entries in system page table:

Indicates the number of page table entries not currently in use by the system.

Number

The maximum number of System PTEs that a server can have is set when the server boots. In heavily-used servers, you can run out of system PTEs. You can use the registry to increase the number of system PTEs, but that encroaches into the paged pool area, and you could run out of paged pool memory. Running out of either one is bad, and the goal should be to tune your server so that you run out of both at the exact same time. Typically, the value of this metric should be above 5000.

Pages read from disk:

Indicates the average number of times per second the disk was read to resolve hard fault paging.

Reads/Sec

 

Pages written to disk:

Indicates the average number of times per second the pages are written to disk to free up the physical memory.

Writes/Sec

 

Memory page ins:

Indicates the number of times per second that a process needed to access a piece of memory that was not in its working set, meaning that the system had to retrieve it from the page file.

Pages/Sec

 

Memory page outs:

Indicates the number of times per second the system decided to trim a process's working set by writing some memory to disk in order to free up physical memory for another process.

Pages/Sec

This value is a critical measure of the memory utilization on a server. If this value never increases, then there is sufficient memory in the system. Instantaneous spikes of this value are acceptable, but if the value itself starts to rise over time or with load, it implies that there is a memory shortage on the server.

Non-paged pool kernel memory size:

Indicates the total size of the kernel memory nonpaged pool.

MB

The kernel memory nonpage pool is an area of system memory (that is, physical memory used by the operating system) for kernel objects that cannot be written to disk, but must remain in physical memory as long as the objects are allocated. Typically, there should be no more than 100 MB of non-paged pool memory being used.

Memory paged pool size:

Indicates the total size of the Paged Pool.

MB

If the Paged Pool starts to run out of space (when it's 80% full by default), the system will automatically take some memory away from the System File Cache and give it to the PagedPool. This makes the System File Cache smaller. However, the system file cache is critical, and so it will never reach zero. Hence, a significant increase in the paged pool size is a problem. This metric is a useful indicator of memory leaks in a system. A memory leak occurs when the system allocates more memory to a process than the process gives back to thepool. Any time of process can cause a memory leak. If the amount of pagedpool data keeps increasing even though the workload on the server remains constant, it is an indicator of a memory leak.

Committed memory in use:

Indicates the committed bytes as a percentage of the Commit Limit.

 

Percent

Whenever this measure exceeds 80-90%, application requests to allocate memory in the virtual memory (page file). This ratio can be reduced by increasing the Physical memory or the Page file.

Pool non-paged failures:

Indicates the number of times allocations have failed from non paged pool.

Number

Generally, a non-zero value indicates a shortage of physical memory.

Pool paged failures:

Indicates the number of times allocations have failed from paged pool.

Number

A non-zero value indicates a shortage of physical memory.

Copy read hits:

Indicates what percent of read I/O being served is coming from system cache, not disk.

Percentage

This is an important counter for applications like the Citrix Provisioning server that stream large volumes of data. If the RAM cache of the server is not sufficiently large, a lot of the I/O requests will be served from the disk, and not the system cache. This will reduce performance. Hence, it is critical to monitor this metric. The higher the value, the better the performance you can see from the server.

Copy reads:

Indicates how many hits you are really getting.

Reads/Sec

A copy read is a file read operation that is satisfied by a memory copy from a page in the cache to the application's buffer. The LAN redirector uses this method for retrieving information from the cache, as does the LAN server for small transfers. This method is also used by the disk file systems.