| Measurement |
Description |
Measurement
Unit |
Interpretation |
| Machine_memory |
Indicates the total amount of machine memory on the ESX server. |
MB |
|
| Console_memory |
Indicates the amount of machine memory allocated to the ESX Server Service Console - this console provides an execution environment for monitoring and administering an ESX Server system. |
MB |
|
| Kernel_memory |
Indicates the amount of machine memory being used by the ESX Server VMKernel. |
MB |
|
| NonKernel_memory |
Indicates the amount of machine memory being used by everything other than the ESX Server Service Console and ESX Server VMKernel. This is the amount of memory used by the guests. |
MB |
The VMkernel manages all machine memory, except for the memory that is allocated to the service console. The VMkernel dedicates part of this managed machine memory for its own use. The rest is available for use by virtual machines. Virtual machines use machine memory for two purposes:
- each virtual machine requires its own memory and
- the VMM requires some memory for its code and data
|
| Machine_free_memory |
Indicates the amount of machine memory that is available for use. |
MB |
A very low value of free memory is also an indication of high memory utilization on a host. |
| Pct_free_memory |
Indicates the percentage of machine memory that is available for use. |
Percent |
A very low value for this measure is an indication of high memory utilization on a host. |
| Console_free_memory |
Indicates the amount of memory allocated to the service console that is still available for use. |
MB |
A low value indicates that the service console, which is the execution environment for monitoring and administering an ESX server, is consuming too much memory. The detailed diagnosis of this measure, if enabled, lists the processes executing on the service console that are currently consuming excessive memory. |
| Swap_current |
Indicates the current swap usage of the ESX server. |
MB |
Swap space is an area on disk that temporarily holds a process memory image. When physical memory demand is sufficiently low, process memory images are brought back into physical memory from the swap area on disk. Having sufficient swap space enables the system to keep some physical memory free at all times.Typically, swap space usage for the ESX host should be low. Since access from RAM is much faster than access from physical disk, excessive usage of swap memory will slow down the performance of the ESX server, as also the virtual machines executing on it. A high rate of swap reads and writes can thus be a cause for concern. |
| Swap_target |
Indicates where the ESX server expects the swap usage to be. |
MB |
| Swap_reads |
Indicates the rate at which memory is swapped in by the ESX server from the disk. |
Reads/Sec |
| Swap_writes |
Indicates the rate at which memory is swapped to the disk by the ESX server. |
Writes/Sec |
| Balloon_mem_current |
Indicates the total amount of physical memory currently reclaimed by the ESX server using the vmmemctl modules. |
MB |
The vmmectl driver that is installed on a virtual machine, emulates an increase or decrease inmemory pressure on the guest operating system; this way, it forces the guest OS to placememory pages into its local swap file. This driver differs from the VMware swap file method as it forces the operating system to determine what memory it wishes to page. Once the memory is paged locally on the guest operating system, the free physical pages of memory may be reallocated to other guests. As the ESX hosts sees that memory demand has been reduced, it will instruct vmmemctl to"deflate" the balloon and reduce pressure on the guest OS to page memory. The maximum amount of memory that can be reclaimed from a guest may be configured by modifying the "sched.mem.maxmemctl" advanced option.If the memory reclaimed (i.e., the Balloon_mem_current) is very low, it indicates excessive memory usage by the guests. Under such circumstances, you might want to consider allocating more memory to the guests. Similarly, if the value of the Balloon_mem_current measure is dangerously close to the Balloon_mem_max measure, it indicates that the guest operating systems are left with very limited reclaimable memory. This, once again, is indicative of high memory pressure on the guests. A re-look at the memory allocations to the guests is hence recommended. |
| Balloon_mem_target |
Indicates the total amount of physical memory the ESX server attempts to reclaim from the guests using the vmmemctl modules. |
MB |
| Balloon_mem_max |
Indicates the maximum amount of physical memory the ESX server can reclaim using the vmmemctl modules. |
MB |
This test will report the following measures only if the procedure discussed in Section 9 of the Monitoring VMware Infrastructures is followed: