Esxi Host Memory Slots
2021年11月17日Register here: http://gg.gg/wwyvm
Excessive memory consumption can cause performance issues for hosts and virtual machines. When a host is under pressure in terms of available physical memory, it may have to begin swapping memory to disk, which will negatively affect virtual machine performance.
Low - If the host’s memory usage is above the Low state, ESXi host will stop creating the new pages for Virtual machines and continues compressing and swapping until free up more memory. With prior to the vSphere 5, High was set by default at 6%, Soft at 4%, Hard at 2%, and Low at 1%.
*This article provides steps to find information about the physical memory installed in each slot on an ESX/ESXi host. Resolution To determine how much RAM is installed in each slot on an ESX/ESXi host.
*VMware ESXi: The Purpose-Built Bare Metal Hypervisor. Discover a robust, bare-metal hypervisor that installs directly onto your physical server. With direct access to and control of underlying resources, VMware ESXi effectively partitions hardware to consolidate applications and cut costs.
I’ve previously written an article about monitoring memory performance using esxtop, but will cover the main metrics to be aware of when troubleshooting memory performance issues here. The memory page in esxtop is a good place to start:
There is a lot of data here, so I’ll break down what some of the metrics are.
*PMEM/MB – This is the amount of physical memory on the host. In this case it is 4095 MB. VMK refers to the memory being used by the VMKernel, Other is the amount of memory being used by everything other than the VMkernel and Free, is the amount of free memory.
*VMKMEM/MB– This is the amount of physical memory currently managed by the VMkernel. 4077 MB. ‘Min Free’ is the amount of memory that the VMkernel aims to keep free (this can be tweaked with the mem.memfreepct advanced setting). ‘rsvd’ is the amount of memory reserved by resource pools. ‘ursvd’ is the amount of memory that is currently unreserved.
*PSHARE– This is the savings made by Transparent Page Sharing – The memory savings here are 2758MB from the 4 virtual machines that are running.
*State – The host is currently in the ‘high’ state. This is an indication of whether the host is currently reclaiming memory. More on this later.
*SWAP/MB – This is the total memory swapped out for all virtual machines on the host. ‘curr’ shows the current swap usage, r/s and w/s show the rate that ESXi is swapping memory to disk
*ZIP/MB – These are the memory compression statistics
*MEMCTL/MB – These are the memory balloon statistics.
Below these are the virtual machine specific counters, which include:
*MEMSZ – the amount of memory allocated to the virtual machine
*MCTLSZ – When > 0 the host is forving VMs to inflate balloon driver to reclaim memory.
*SWR/s – If > 0 then the host is swapping memory in from disk.
*SWW/s– If > 0 then the host is swapping memory out to disk.
*SWCUR – The amount of swap space in use by the VM. A value greater than zero indicates that the host has previously swapped memory.
*SWTGT – The amount of swap space the host anticipates would be in use by a VM.
*SWPWT – Percentage of time a virtual machine is waiting for memory to be swapped back in from disk. A value exceeding five should be acted upon.
*MCTL – Displays whether or not the balloon driver is installed on the virtual machine.
*ZIP– If > 0 the host is actively compressing memory.
*UNZIP– if > 0 the host has accessed compressed memory.Host Swapping and Memory Reclaimation
When a host is suffering from a lack of memory resources it will attempt to reclaim memory that it has already handed out to virtual machines. There are four host ‘free memory’ states, which indicate whether a host is attempting to reclaim memory. These are High, Soft, Hard and Low.
The state the host is currently in can be see clearly on the memory screen in ESXTOP:
The example output above shows a host in the ‘High’ state, which means it is not currently under memory contention. If the host is in the ‘Soft’ state then ballooning is used to reclaim memory. In ‘Hard’, Swapping and compression is used to reclaim, and when the host is in the ‘Low’ state, ballooning, swapping and compression are all used to attempt to reclaim memory. Swapping will have a negative affect on the performance of the host and virtual machines – you can monitor swapping by using the Swap In and Swap Out metrics in vCenter. On a healthy host, these values should always be low:
If the host has been or is under memory contention you will see something more along the lines of:
It is likely that the state will have changed in esxtop at this time:
As shown above, the host is in the ‘soft’ state, meaning that it is actively ballooning in order to reclaim memory. We can confirm that ballooning has occurred by adding the Balloon metric to the chart:
The state is good indication of what shape the hosts memory is in. If the host is actively swapping there will be performance degradation for the virtual machine(s). To see whether swapping is affecting a given virtual machine, you can use the %SWPWT metric, which is found on the CPU page in esxtop:
%SWPWT shows the percentage of time that a virtual machine is waiting for it’s pages to be swapped. In the example above we can see that the XP2 (and to a lesser extent, XP1) virtual machine is waiting for it’s pages to be swapped, which will negatively affect the VMs performance. Any value above zero indicates a problem. If the value is above 5 then the cause should be investigated immediately.
With this example the cause was due to memory over commitment, with both of the XP virtual machines using all their memory allocation at the same time. It’s also worth checking whether the balloon drivers are present in the virtual machines that are swapping, as without the driver the host may be forced to swap rather than use ballooning (which has a lower impact). The balloon drivers get installed onto the guest VM when you install VMtools. You can check that the balloon drivers are present and enabled by looking at the ‘MCTL?’ column:
A ‘Y’ indicates that the balloon drivers are present in the virtual machine and enabled.
During upgradation of a DELL PowerEdge R730/R830 server, we have increased the RAM from 24 GB to 88 GB and CPU from 1 to 2. After booting the system when we have checked from the BIOS we found the system is showing 2 CPU but showing RAM only 72 GB, 2 RAM of 8 GB was not installed correctly. At that time we were not able to identify the slots for which RAM was detected.
Later i googled that how to find system info, processor info, cache info, memory info, port connector details etc. and found the command smbiosDump through which we can get all the details related to system hardware through ESXi command line interface (CLI) after login as root.How to check System and Hardware Information on a Linux ServerHP-UX command to get Physical Memory InformationEsxi Check Memory Slots
To log in to ESXi shell as a root, SSH service should be enabled and running on the ESXi host. To enable it you need to login to ESXi host through vSphere Client and go to Configuration >> Software >> Security Profile >> Properties select SSH click on options and start the SSH service.
After login to ESXi host through run the smbiosDump command to get the system information.
Below command show that maximum memory which can be installed on the server, maximum 2048 GB memory can be installed on this serverEsxi Host Memory Slots Download
To see the details of all physical memory installed on the server with the details of location, size etc.
Processor info showing the details of the both processorsEsxi Host Memory Slots Online
Cache Info showing the details of the L1, L2 and L3 cache for both the processors
Note: I have executed commands on ESXi host running on the ESXi 6.0.0Related Posts
Register here: http://gg.gg/wwyvm
https://diarynote.indered.space
Excessive memory consumption can cause performance issues for hosts and virtual machines. When a host is under pressure in terms of available physical memory, it may have to begin swapping memory to disk, which will negatively affect virtual machine performance.
Low - If the host’s memory usage is above the Low state, ESXi host will stop creating the new pages for Virtual machines and continues compressing and swapping until free up more memory. With prior to the vSphere 5, High was set by default at 6%, Soft at 4%, Hard at 2%, and Low at 1%.
*This article provides steps to find information about the physical memory installed in each slot on an ESX/ESXi host. Resolution To determine how much RAM is installed in each slot on an ESX/ESXi host.
*VMware ESXi: The Purpose-Built Bare Metal Hypervisor. Discover a robust, bare-metal hypervisor that installs directly onto your physical server. With direct access to and control of underlying resources, VMware ESXi effectively partitions hardware to consolidate applications and cut costs.
I’ve previously written an article about monitoring memory performance using esxtop, but will cover the main metrics to be aware of when troubleshooting memory performance issues here. The memory page in esxtop is a good place to start:
There is a lot of data here, so I’ll break down what some of the metrics are.
*PMEM/MB – This is the amount of physical memory on the host. In this case it is 4095 MB. VMK refers to the memory being used by the VMKernel, Other is the amount of memory being used by everything other than the VMkernel and Free, is the amount of free memory.
*VMKMEM/MB– This is the amount of physical memory currently managed by the VMkernel. 4077 MB. ‘Min Free’ is the amount of memory that the VMkernel aims to keep free (this can be tweaked with the mem.memfreepct advanced setting). ‘rsvd’ is the amount of memory reserved by resource pools. ‘ursvd’ is the amount of memory that is currently unreserved.
*PSHARE– This is the savings made by Transparent Page Sharing – The memory savings here are 2758MB from the 4 virtual machines that are running.
*State – The host is currently in the ‘high’ state. This is an indication of whether the host is currently reclaiming memory. More on this later.
*SWAP/MB – This is the total memory swapped out for all virtual machines on the host. ‘curr’ shows the current swap usage, r/s and w/s show the rate that ESXi is swapping memory to disk
*ZIP/MB – These are the memory compression statistics
*MEMCTL/MB – These are the memory balloon statistics.
Below these are the virtual machine specific counters, which include:
*MEMSZ – the amount of memory allocated to the virtual machine
*MCTLSZ – When > 0 the host is forving VMs to inflate balloon driver to reclaim memory.
*SWR/s – If > 0 then the host is swapping memory in from disk.
*SWW/s– If > 0 then the host is swapping memory out to disk.
*SWCUR – The amount of swap space in use by the VM. A value greater than zero indicates that the host has previously swapped memory.
*SWTGT – The amount of swap space the host anticipates would be in use by a VM.
*SWPWT – Percentage of time a virtual machine is waiting for memory to be swapped back in from disk. A value exceeding five should be acted upon.
*MCTL – Displays whether or not the balloon driver is installed on the virtual machine.
*ZIP– If > 0 the host is actively compressing memory.
*UNZIP– if > 0 the host has accessed compressed memory.Host Swapping and Memory Reclaimation
When a host is suffering from a lack of memory resources it will attempt to reclaim memory that it has already handed out to virtual machines. There are four host ‘free memory’ states, which indicate whether a host is attempting to reclaim memory. These are High, Soft, Hard and Low.
The state the host is currently in can be see clearly on the memory screen in ESXTOP:
The example output above shows a host in the ‘High’ state, which means it is not currently under memory contention. If the host is in the ‘Soft’ state then ballooning is used to reclaim memory. In ‘Hard’, Swapping and compression is used to reclaim, and when the host is in the ‘Low’ state, ballooning, swapping and compression are all used to attempt to reclaim memory. Swapping will have a negative affect on the performance of the host and virtual machines – you can monitor swapping by using the Swap In and Swap Out metrics in vCenter. On a healthy host, these values should always be low:
If the host has been or is under memory contention you will see something more along the lines of:
It is likely that the state will have changed in esxtop at this time:
As shown above, the host is in the ‘soft’ state, meaning that it is actively ballooning in order to reclaim memory. We can confirm that ballooning has occurred by adding the Balloon metric to the chart:
The state is good indication of what shape the hosts memory is in. If the host is actively swapping there will be performance degradation for the virtual machine(s). To see whether swapping is affecting a given virtual machine, you can use the %SWPWT metric, which is found on the CPU page in esxtop:
%SWPWT shows the percentage of time that a virtual machine is waiting for it’s pages to be swapped. In the example above we can see that the XP2 (and to a lesser extent, XP1) virtual machine is waiting for it’s pages to be swapped, which will negatively affect the VMs performance. Any value above zero indicates a problem. If the value is above 5 then the cause should be investigated immediately.
With this example the cause was due to memory over commitment, with both of the XP virtual machines using all their memory allocation at the same time. It’s also worth checking whether the balloon drivers are present in the virtual machines that are swapping, as without the driver the host may be forced to swap rather than use ballooning (which has a lower impact). The balloon drivers get installed onto the guest VM when you install VMtools. You can check that the balloon drivers are present and enabled by looking at the ‘MCTL?’ column:
A ‘Y’ indicates that the balloon drivers are present in the virtual machine and enabled.
During upgradation of a DELL PowerEdge R730/R830 server, we have increased the RAM from 24 GB to 88 GB and CPU from 1 to 2. After booting the system when we have checked from the BIOS we found the system is showing 2 CPU but showing RAM only 72 GB, 2 RAM of 8 GB was not installed correctly. At that time we were not able to identify the slots for which RAM was detected.
Later i googled that how to find system info, processor info, cache info, memory info, port connector details etc. and found the command smbiosDump through which we can get all the details related to system hardware through ESXi command line interface (CLI) after login as root.How to check System and Hardware Information on a Linux ServerHP-UX command to get Physical Memory InformationEsxi Check Memory Slots
To log in to ESXi shell as a root, SSH service should be enabled and running on the ESXi host. To enable it you need to login to ESXi host through vSphere Client and go to Configuration >> Software >> Security Profile >> Properties select SSH click on options and start the SSH service.
After login to ESXi host through run the smbiosDump command to get the system information.
Below command show that maximum memory which can be installed on the server, maximum 2048 GB memory can be installed on this serverEsxi Host Memory Slots Download
To see the details of all physical memory installed on the server with the details of location, size etc.
Processor info showing the details of the both processorsEsxi Host Memory Slots Online
Cache Info showing the details of the L1, L2 and L3 cache for both the processors
Note: I have executed commands on ESXi host running on the ESXi 6.0.0Related Posts
Register here: http://gg.gg/wwyvm
https://diarynote.indered.space
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