The memory metric group tracks memory statistics for virtual machines, hosts, resource pools, and compute resources.

Interpret the data counter definitions in the context of the entity to which it applies, as follows:

For virtual machines, memory refers to guest physical memory. Guest physical memory is the amount of physical memory presented as a virtual-hardware component to the virtual machine, at creation time, and made available when the virtual machine is running.

For hosts, memory refers to machine memory. Machine memory is the random-access memory (RAM) that is actually installed in the hardware that comprises the ESX/ESXi host.

Memory Data Counters lists the memory data counters.

Note

Only a subset of memory counters appear in the overview charts. To view all memory data counters, use the advanced performance charts.

Memory Data Counters

Counter

Label

Description

Entity

V

H

R

C

active

Memory Active

Amount of memory actively used, as estimated by VMkernel. Active memory is based on the current workload of the virtual machine or host.

VM

Amount of guest physical memory in use by the virtual machine. Active memory is estimated by VMkernel statistical sampling and represents the actual amount of memory the virtual machine needs.

Host

Sum of the active guest physical memory of all powered on virtual machines on the host, plus memory used by basic VMKernel applications on the host.

Stats Type: absolute

Unit: KiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

consumed

Memory Consumed

VM

Amount of guest physical memory consumed by the virtual machine for guest memory. Consumed memory does not include overhead memory. It includes shared memory and memory that might be reserved, but not actually used. It does not include overhead memory.

vm consumed memory = memory granted - memory saved due to memory sharing

Host

Amount of machine memory used on the host. Consumed memory includes memory used by virtual machines, the service console, VMkernel, and vSphere services, plus the total consumed memory for all running virtual machines.

host consumed memory = total host memory - free host memory

Cluster

Amount of host machine memory used by all powered on virtual machines in the cluster. A cluster's consumed memory consists of virtual machine consumed memory and overhead memory. It does not include host-specific overhead memory, such as memory used by the service console or VMkernel.

Stats Type: absolute

Unit: KiloBytes

Rollup Type: average (min/max)

Collection Level: 1(4)

granted

Memory Granted

VM

The amount of guest physical memory that is mapped to machine memory. Includes shared memory amount. The amount of guest physical memory currently mapped to machine memory, including shared memory, but excluding overhead.

Host

The total of all granted metrics for all powered-on virtual machines, plus memory for vSphere services on the host.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

heap

Memory Heap

Amount of VMkernel virtual address space dedicated to VMkernel main heap and related data.

This counter is for internal use only and is not useful for performance monitoring.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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heapfree

Memory Heap Free

Amount of free address space in the VMkernel’s main heap. Heap Free varies, depending on the number of physical devices and various configuration options. There is no direct way for the user to increase or decrease this statistic.

This counter is for internal use only and is not useful for performance monitoring.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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mementitlement

Worst Case Allocation

(virtual machine Resource Allocation tab)

Memory allocation as calculated by the VMkernel scheduler based on current estimated demand, and the reservation, limit, and shares policies set for all virtual machines and resource pools in the host or cluster.

This counter is for internal use only and is not useful for performance monitoring.

Stats Type: absolute

Unit: megaBytes

Rollup Type: latest

Collection Level: 1

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memUsed

Memory Used

Amount of used memory. Sum of the memory used by all powered on virtual machines and vSphere services on the host.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 3

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overhead

Memory Overhead

Amount of additional machine memory allocated to a virtual machine for overhead. The overhead amount is beyond the reserved amount.

VM

Amount of machine memory used by the VMkernel to run the virtual machine.

Host

Total of all overhead metrics for powered-on virtual machines, plus the overhead of running vSphere services on the host.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 1(4)

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reservedCapacity

Memory Reserved Capacity

Total amount of memory reservation used by powered on VMs and vSphere services on the host. Includes overhead amount.

Stats Type: absolute

Unit: megaBytes

Rollup Type: average

Collection Level: 2

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shared

Memory Shared

VM

Amount of guest physical memory that is shared with other virtual machines (through the VMkernel’s transparent page-sharing mechanism, a RAM de-duplication technique). The value of shared includes the size of the zero memory area.

Host

Sum of the shared memory values of all powered-on virtual machines, plus the amount for the vSphere services on the host. The host’s Memory Shared may be larger than the amount of machine memory if memory is overcommitted (the aggregate virtual machine configured memory is much greater than machine memory). The value of this statistic reflects how effective transparent page sharing and memory overcommitment are for saving machine memory.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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sharedcommon

Memory Shared Common

Amount of machine memory that is shared by all powered-on virtual machines and vSphere services on the host.

Memory Shared - Memory Shared Common = Host memory saved by sharing

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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state

Memory State

Amount of free machine memory on the host. VMkernel has four free-memory thresholds that affect the mechanisms used for memory reclamation.

0 (High)

Free memory >= 6% of machine memory - service console memory

1 (Soft)

Free memory >= 4% of machine memory - service console memory

2 (Hard)

Free memory >= 2% of machine memory - service console memory

3 (Low)

Free memory >= 1% of machine memory - service console memory

For 0 and 1, swapping is favored over ballooning. For 2 and 3, ballooning is favored over swapping.

Stats Type: absolute

Unit: number

Rollup Type: latest

Collection Level: 2

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swapin

Memory Swap In

Amount of memory that has been swapped in to memory from disk.

VM

Total amount of memory data that has been read in from the virtual machine’s swap file to machine memory by the VMkernel. This statistic refers to VMkernel swapping and not to guest OS swapping.

Host

Sum of memory swapin of all powered on VMs on the host.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 1(4)

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swapinRate

Memory Swap In Rate

Rate at which memory is swapped from disk into active memory during the current interval. This counter applies to virtual machines and is generally more useful than the swapin counter to determine if the virtual machine is running slow due to swapping, especially when looking at real-time statistics.

Stats Type: rate

Unit: kiloBytesPerSecond

Rollup Type: average (min/max)

Collection Level: 1(4)

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swapout

Memory Swap Out

Amount of memory that has been swapped out to disk.

VM

Total amount of memory data that has been written out to the virtual machine’s swap file from machine memory by the VMkernel. This statistic refers to VMkernel swapping and not to guest OS swapping.

Host

Sum of Memory Swap Out of all powered on VMs on the host.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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swapoutRate

Memory Swap Out Rate

Rate at which memory is being swapped from active memory to disk during the current interval. This counter applies to virtual machines and is generally more useful than the swapout counter to determine if the virtual machine is running slow due to swapping, especially when looking at real-time statistics.

Stats Type: rate

Unit: kiloBytesPerSecond

Rollup Type: average (min/max)

Collection Level: 1(4)

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swapped

Memory Swapped

Current amount of guest physical memory swapped out to the virtual machine’s swap file by the VMkernel. Swapped memory stays on disk until the virtual machine needs it. This statistic refers to VMkernel swapping and not to guest OS swapping.

swapped = swapin +swapout

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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swaptarget

Memory Swap Target

Amount of memory available for swapping.

Target value for the virtual machine swap size, as determined by the VMkernel. The VMkernel sets a target for the level of swapping for each virtual machine, based on a number of factors.

If Memory Swap Target is greater than Memory Swap, then the VMkernel will start swapping, causing more virtual machine memory to be swapped out. This will generally happen quickly. If Memory Swap Target is less than Memory Swap, then the VMkernel will stop swapping.

Since swapped memory stays swapped until the virtual machine accesses it, Memory Swapped can be greater than Memory Swap Target, possibly for a prolonged period of time. This simply means that the swapped memory is not currently needed by the virtual machine and is not a cause for concern.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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swapunreserved

Memory Swap Unreserved

Amount of memory that is unreserved by swap.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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swapused

Memory Swap Used

Amount of memory that is used by swap. Sum of Memory Swapped of all powered on virtual machines and vSphere services on the host.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 1(4)

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sysUsage

Memory Used by VMkernel

Amount of memory used by the VMkernel. Amount of machine memory used by the VMkernel for “core” functionality (such as its own internal uses, device drivers, etc). It does not include memory used by VMs or by vSphere services.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

totalmb

Memory Total

Total amount of machine memory of all hosts in the cluster that is available for virtual machine memory (physical memory for use by the Guest OS) and virtual machine overhead memory.

Memory Total = Aggregate host machine memory - (VMkernel memory + Service Console memory + other service memory)

Stats Type: absolute

Unit: megaBytes

Rollup Type: average

Collection Level: 1

VC/ESX: Yes/No

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unreserved

Memory Unreserved

Amount of memory that is unreserved. Memory reservation not used by the Service Console, VMkernel, vSphere services and other powered on VMs’ user-specified memory reservations and overhead memory.

Note

This statistic is no longer relevant to virtual machine admission control, as reservations are now handled through resource pools.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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usage

Memory Usage

Memory usage as percentage of total configured or available memory.

VM

memory usage = memory active ÷ virtual machine physical memory size

Host

memory usage = memory consumed ÷ host configured memory size

Cluster

memory usage = memory consumed + memory overhead ÷ effectivemem

Stats Type: absolute

Unit: percent

Rollup Type: average (min/max)

Collection Level: 1(4)

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vmmemctl

Memory Balloon

Amount of memory allocated by the virtual machine memory control driver, which is installed with VMware Tools.

VM

Amount of guest physical memory that is currently reclaimed from the virtual machine through ballooning. This is the amount of guest physical memory that has been allocated and pinned by the balloon driver.

Host

Sum of Memory Balloon of all powered on virtual machines and vSphere services on the host. If the balloon target value is greater than the balloon value, the VMkernel inflates the balloon, causing more virtual machine memory to be reclaimed. If the balloon target value is less than the balloon value, the VMkernel deflate the balloon, which allows the virtual machine to consume additional memory if needed.

Virtual machines initiate memory reallocation. Therefore, it is possible to have a balloon target value of 0 and balloon value greater than 0.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 1(4)

vmmemctltarget

Memory Balloon Target

Amount of memory that can be used by memory control.

This is the target value for the virtual machine’s Memory Balloon value, as determined by the VMkernel. The VMkernel sets a target for the level of ballooned memory for each virtual machine, based on a number of factors.

If Memory Balloon Target is greater than Memory Balloon, the VMkernel inflates the balloon, causing more virtual machine memory to be reclaimed and Memory Balloon to increase.

If Memory Balloon Target is less than Memory Balloon, the VMkernel deflates the balloon, allowing the virtual machine to map/consume additional memory if it needs it. Memory Balloon decreases as the VMkernel deflates the balloon.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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zero

Memory Zero

Amount of memory that is zeroed out (contains only 0s). This statistic is included in Memory Shared.

VM

Amount of guest physical zero memory that is shared through transparent page sharing. Zero memory is simply memory that is all zeroes.

Host

Sum of Memory Zero of all powered on VMs and vSphere services on the host.

Stats Type: absolute

Unit: kiloBytes

Rollup Type: average (min/max)

Collection Level: 2(4)

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