The following are the important memory counters for Microsoft Exchange Server.
| Object | Counter |
| Memory | Pages/sec |
| Page Faults/sec | |
| Available Bytes | |
| Committed Bytes | |
| Process | Page Faults/sec |
| Working Set |
The Pages/sec counter indicates the rate at which pages are physically read or written on the paging drive. This indicates the contribution that paging makes to the demand for the disk.
The Page Faults/sec counter indicates the rate at which pages are faulted into the working sets of processes. A page fault occurs when a process refers to a virtual memory page that is not in its working set in main memory. The number of pages actually being read and written to disk is much less than the number of page faults because of the page pool in the virtual memory system. The page faults are of interest if you are running other services in addition to Microsoft Exchange Server. In this situation, you can examine the rate of page faults on a per-process basis and determine where they are occurring. Then, with this information, you can make application-tuning changes. For example, you might consider carefully adjusting the trade-off between the information store buffer pool and the system memory pool. Also, by checking the per-process working sets, you can identify the major memory allocations. If your paging rate is over a small amount (for example 20 pages/sec), consider adding memory.
The Available Bytes counter indicates how much physical memory is available at any given time. The system adjusts working sets of processes to keep this above a certain threshold, generally 4 MB. If this level is approached, you should see higher paging and page fault rates. The Committed Bytes counter indicates the amount of virtual address space that the system has committed to applications. This must be backed by the paging file on the disk, so make sure that there is space in the paging file. Anticipate memory issues by tracking trends in available and committed memory.