Memory Usage - OS Test

Memory shortage on a VM can affect the memory allocation to crucial processes that are being executed on the VM, which in turn can adversely impact the performance of the applications running on the VM. One of the primary reasons for Memory shortage is that of precious memory space being unnecessarily hogged by Modified and Standby memory lists that hold temporary/unused data. The Modified and Standby memory lists cache temporary data when the applications/services run in the VM. These temporary data will no longer be used by the applications/services thus hogging memory space unnecessarily. Therefore, administrators should clear the cached data on a regular basis. If the cached data is not cleared regularly, sometimes, you may not be able to allocate memory to the business-critical processes, which will seriously impact service/application delivery and impair user experience. Therefore, it is imperative that you should closely observe if the memory shortage occurs due to data growth of the Modified and Standby memory lists and proactively initiate remedial actions before it causes severe memory contention on the VM. This can be achieved with the help of the Memory Usage - OS test.

This test auto discovers the VMs on the virtual server and periodically monitors the memory usage of each VM, checks whether adequate physical memory is available to the VM, and if not, promptly alerts users to the same. In the process, the test also reveals the VMs on which the memory space is abnormally hogged by Modified or Standby memory list. This way, VMs that experience potential memory contention are brought to your attention. Besides warning you of memory contention that Modified/Standby memory lists can cause, the test also empowers you to avoid probable memory shortage by initiating automated actions. These automated actions can be closely tracked using detailed diagnostics.

Target of the test : A Proxmox Hypervisor

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for each virtual machine on the virtual server.

Configurable parameters for the test
Parameter Description

Test period

How often should the test be executed.

Host

The IP address of the host for which this test is to be configured.

Port

The port at which the specified host listens. By default, this will be NULL.

Proxmox Node Name

Specify the name of the Proxmox node that you wish to monitor in this text box. By default, this parameter is set to none indicating that the test monitor all the nodes in the target hypervisor.

Ignore VMs Inside View

Administrators of some high security Proxmox environments might not have permissions to internally monitor one/more VMs. The eG agent can be configured to not obtain the 'inside view' of such ‘inaccessible’ VMs using the Ignore VMs Inside View parameter. Against this parameter, you can provide a comma-separated list of VM names, or VM name patterns, for which the inside view need not be obtained. For instance, yourIgnore VMs Inside View specification can be: *xp,*lin*,win*,vista. Here, the * (asterisk) is used to denote leading and trailing spaces (as the case may be). By default, this parameter is set to none indicating that the eG agent obtains the inside view of all VMs on a Proxmox Hypervisor by default.

Note:

While performing VM discovery, the eG agent will not discover the operating system of the VMs configured in the Ignore VMs Inside View text box.

Exclude IP

Typically, when performing VM discovery, the eG agent automatically discovers the operating system on which every VM runs, and all the IP addresses that each VM supports. If two are more VMs on a target vSphere server are in a VM cluster, then the eG agent will also auto-discover the cluster IP address. Since the cluster IP address is shared by all VMs in the cluster, this IP address will be in the discovery list of every VM in the cluster. In this case, if the eG agent attempts to obtain the 'inside view' of each VM in a cluster using their cluster IP address, incorrect metrics may be reported sometimes. To avoid this, you may want to instruct the eG agent to not use the cluster IP address when collecting 'inside view' metrics. For this, specify a comma-separated list of cluster IP addresses to be excluded in the EXCLUDE IP text box.

Ignore WINNT

By default, the eG agent does not support the inside view for VMs executing on Windows operating systems. Accordingly, the Ignore WINNT flag is set to Yes by default.

Exclude VMs

Administrators of some virtualized environments may not want to monitor some of their less-critical VMs - for instance, VM templates - both from 'outside' and from 'inside'. The eG agent in this case can be configured to completely exclude such VMs from its monitoring purview. To achieve this, provide a comma-separated list of VMs to be excluded from monitoring in the Exclude VMs text box. Instead of VMs, VM name patterns can also be provided here in a comma-separated list. For example, your Exclude VMs specification can be: *xp,*lin*,win*,vista. Here, the * (asterisk) is used to denote leading and trailing spaces (as the case may be). By default, this parameter is set to none indicating that the eG agent obtains the inside and outside views of all VMs on a virtual host by default. By providing a comma-separated list of VMs/VM name patterns in the Exclude VMs text box, you can make sure the eG agent stops collecting 'inside' and 'outside' view metrics for a configured set of VMs.

Domain, Admin User, Admin Password, and Confirm Password

By default, this test connects to each virtual guest remotely and attempts to collect “inside view” metrics. In order to obtain a remote connection, the test must be configured with user privileges that allow remote communication with the virtual guests. The first step towards this is to specify the Domain within which the virtual guests reside. The Admin User and Admin Password will change according to the Domain specification. Discussed below are the different values that the Domain parameter can take, and how they impact the Admin User and Admin Password specifications:

  • If the VMs belong to a single domain : If the guests belong to a specific domain, then specify the name of that domain against the Domain parameter. In this case, any administrative user in that domain will have remote access to all the virtual guests. Therefore, an administrator account in the given domain can be provided in the Admin User field and the corresponding password in the Admin Password field. Confirm the password by retyping it in the Confirm Password text box.
  • If the guests do not belong to any domain (as in the case of Linux guests) : In this case, specify "none" in the Domain field, and specify a local administrator account name in the Admin User below.

    Prior to this, you need to ensure that the same local administrator account is available or is explicitly created on each of the virtual machines to be monitored. Then, proceed to provide the password of the Admin User against Admin Password, and confirm the password by retyping it in the Confirm Password text box.

    If key-based authentication is implemented between the eG agent and the SSH daemon of a Linux guest, then, in the Admin User text box, enter the name of the user whose <USER_HOME_DIR> (on that Linux guest) contains a .ssh directory with the public key file named authorized_keys. The Admin password in this case will be the passphrase of the public key; the default public key file that is bundled with the eG agent takes the password eginnovations. Specify this as the Admin Password if you are using the default private/public key pair that is bundled with the eG agent to implement key-based authentication. On the other hand, if you are generating a new public/private key pair for this purpose, then use the passphrase that you provide while generating the pair. For the detailed procedure on Implementing Key-based Authentication refer to Troubleshooting the Failure of the eG Remote Agent to Connect to or Report Measures for Linux Guests.

  • If the guests belong to different domains - In this case, you might want to provide multiple domain names. If this is done, then, to access the guests in every configured domain, the test should be configured with the required user privileges; this implies that along with multiple Domain names, multiple Admin User names and Admin Passwords would also have to be provided. To help administrators provide these user details quickly and easily, the eG administrative interface embeds a special configuration page.

    To access this page, simply click on the icon adjacent to the Admin User text box. To know how to use the special page, refer to Configuring Users for VM Monitoring.

  • If the Inside View Using flag is set to ‘eG VM Agent (Windows)’ - In this case, the inside view can be obtained without domain administrator privileges. Therefore, set the Domain, Admin User, and Admin Password parameters to none.

Report By User

While monitoring a Proxmox Hypervisor, the Report By User flag is set to No by default, indicating that by default, the VM operating systems on the target hypervisor are identified using the hostname specified in the operating system. On the other hand, if you want the desktops to be identified using the login of the user who is accessing them, set this flag to Yes. In other words, in VDI environments, this test will, by default, report measures for every username_on_virtualmachinename.

Report Powered OS

This flag becomes relevant only if the Report By User flag is set to ‘Yes’.

If this flag is set to Yes (which is the default setting), then this test will report measures for even those VMs that do not have any users logged in currently. Such guests will be identified by their virtualmachine name and not by the username_on_virtualmachinename. On the other hand, if the Report Powered OS flag is set to No, then this test will not report measures for those VMs to which no users are logged in currently. 

Group Processes with Arguments

By default, the detailed diagnosis of the Used physical memory measure of this test reports the number of instances of each process running on the VM, and the aggregated memory usage (in MB and %) of every process across all its instances. For example, if users to a VM are together having 15 instances of Chrome open on the machine at around the same time, then the detailed diagnosis of the Used physical memory measure will compute and display the collective memory usage of all 15 instances against the Application Name, Chrome. From this, you can quickly identify the exact process that is 'collectively' (i.e., across its instances) over-utilizing the memory. Sometimes, administrators might want to isolate not just the process, but also similar process arguments that are guilty of abnormal memory consumption. This granular insight will take administrators closer to the root-cause of the memory bottleneck on a desktop. For instance, in the Chrome example above, say 8 of the 15 instances are used to access the same YouTube video, and 7 instances are accessing a shopping site. In such a case, if memory usage is aggregated at the URL-level and not the process-level, then administrators can quickly identify which precise URL is draining memory - the YouTube video? or the shopping site? For this, detailed diagnostics should be grouped by process arguments (eg., URLs) and not just by process/application names. To enable grouping by arguments, set the Group Processes With Arguments flag to Yes. By default, this flag is set to No.

Memory Utilization in Percent

By default, this parameter is set to 75 percentage indicating that by default this test will display top-10 memory intensive processes on a VM in the detailed diagnosis of the Physical memory utilized measure only when the memory utilization reaches/exceeds 75 percentage. On the other hand, if the memory utilization is lower than the value specified against this parameter, then, this test displays only top-3 memory intensive processes in the detailed diagnosis of the Physical memory utilized measure so as to conserve storage space on the database. However, this setting can be overridden if required.

Automated Action Enabled

A memory shortage caused due to memory space hogged by modified and standby memory lists has become an increasingly frequent and critical problem. The memory shortage can make a server stutter or run more slowly than usual. Such operational interruptions can make you spend more time on waiting for pages and programs to load, disturbing your work flow and leading to work delays. Moreover, memory shortage can not only impair user productivity, but can also bring crucial business processes to a halt, and can severely degrade overall user experience with the server. To avoid such an outcome, administrators need to rapidly empty the memory space unnecessarily hogged by the modified and standby memory lists. This way, administrators can ensure that adequate memory is always available for executing business-critical processes.

To enable administrators to achieve this, eG Enterprise offers 'Automation Actions'. These actions are governed by the 'Automation Action Enabled' flag.

This flag, if enabled, automatically initiates user-configured actions, so that the memory hogged by modified and standby memory lists can be cleared when memory utilization crosses a configured limit.

Note:

The 'Automation Action Enabled' parameters, once configured, will apply only to the chosen component. These settings will not be applied to other components even if the Apply to other components button is clicked in the Specific Test Configuration page.

Automation Memory Limit

This flag appears only if the Automated Action Enabled flag is enabled.

In this text box, specify the upper limit for memory utilization in percentage beyond which this test should trigger user-configured automation actions. By default, 95 percentage is set against this parameter. When the memory utilization reaches/exceeds the value specified in this text box, the user-configured actions will be automatically triggered. However, you can override this settings if required.

Empty Modified Memory

This flag appears only if the Automated Action Enabled flag is enabled.

Modified memory contains cached data and code that is not actively in use by processes, the system and the system cache. This memory needs to be written out before it will be available for allocation to a process or for system use. You can easily clear this memory using the Empty Modified Memory flag.

By default, this flag is set to No. When this flag is set Yes, amount of memory assigned to the modified list will be automatically cleared if the memory utilization reaches/exceeds the value specified against the Automation Memory Limit parameter.

Empty Standby Memory

This flag appears only if the Automated Action Enabled flag is enabled.

Standby memory is a page of physical memory that is not actively used. When writing a series of frequently used information in the memory area, the programs and services running on the server will use part of memory as cache. The cache should be released and made available after executing programs and services. If the standby memory is not cleared on a regular basis, it can slow down the server operations. Therefore, it is necessary to clear the standby memory at regular intervals. This can easily done using the Empty Standby Memory flag.

By default, this flag is set to No. When this flag is set Yes, memory that is allocated to the standby page list will be automatically cleared if the memory utilization reaches/exceeds the value specified against the Automation Memory Limit parameter.

DD Frequency

Refers to the frequency with which detailed diagnosis measures are to be generated for this test. The default is 1:1. This indicates that, by default, detailed measures will be generated every time this test runs, and also every time the test detects a problem. You can modify this frequency, if you so desire. Also, if you intend to disable the detailed diagnosis capability for this test, you can do so by specifying none against DD frequency.

Detailed Diagnosis

To make diagnosis more efficient and accurate, the eG Enterprise embeds an optional detailed diagnostic capability. With this capability, the eG agents can be configured to run detailed, more elaborate tests as and when specific problems are detected. To enable the detailed diagnosis capability of this test for a particular server, choose the On option. To disable the capability, click on the Off option.

The option to selectively enable/disable the detailed diagnosis capability will be available only if the following conditions are fulfilled:

  • The eG manager license should allow the detailed diagnosis capability
  • Both the normal and abnormal frequencies configured for the detailed diagnosis measures should not be 0.
Measurements made by the test
Measurement Description Measurement Unit Interpretation

Total physical memory

Indicates the total physical memory of this VM.

MB

 

Used physical memory

Indicates the used physical memory of this VM.

MB

The detailed diagnosis of this measure reveals top-10 groups of processes on the VM consuming memory excessively. Using the detailed diagnosis of this measure, you can figure out the amount and percentage of memory consumed by each group of processes, the name of application to which the process group belongs, and the arguments passed to the processes. The arguments for a process can tell you where configuration files are, what passwords might have been used or correct arguments to use when running the process yourself.

Free physical memory

Indicates the free physical memory of the VM.

MB

This measure typically indicates the amount of memory available for use by applications running on the target VM.

On Unix operating systems (AIX and Linux), the operating system tends to use parts of the available memory for caching files, objects, etc. When applications require additional memory, this is released from the operating system cache. Hence, to understand the true free memory that is available to applications, the eG agent reports the sum of the free physical memory and the operating system cache memory size as the value of the Free physical memory measure while monitoring AIX and Linux guest operating systems. 

Physical memory utilized

Indicates the percent usage of physical memory by this VM.

Percent

Ideally, the value of this measure should be low. While sporadic spikes in memory usage could be caused by one/more rogue processes on the VM, a consistent increase in this value could be a cause for some serious concern, as it indicates a gradual, but steady erosion of valuable memory resources. If this unhealthy trend is not repaired soon, it could severely hamper VM performance, causing anything from a slowdown to a complete system meltdown.

You can use the detailed diagnosis of this measure to figure out which processes on the VM are consuming memory excessively.

Available physical memory

Indicates the amount of physical memory, immediately available for allocation to a process or for system use.

MB

Not all of the Available physical memoryis Free physical memory. Typically, Available physical memoryis made up of the Standby List, Free List, and Zeroed List.

When Windows wants to trim a process' working set, the trimmed pages are moved (usually) to the Standby List. From here, they can be brought back to life in the working set with only a soft page fault (much faster than a hard fault, which would have to talk to the disk). If a page stays in the standby List for a long time, it gets freed and moved to the Free List.

In the background, there is a low priority thread (actually, the only thread with priority 0) which takes pages from the Free List and zeros them out. Because of this, there is usually very little in the Free List.

All new allocations always come from the Zeroed List, which is memory pages that have been overwritten with zeros. This is a standard part of the OS' cross-process security, to prevent any process ever seeing data from another. If the Zeroed List is empty, Free List memory is zeroed and used or, if that is empty too, Standby List memory is freed, zeroed, and used. It is because all three can be used with so little effort that they are all counted as "available".

A high value is typically desired for this measure.

Modified memory

Indicates the amount of memory that is allocated to the modified page list.

MB

This memory contains cached data and code that is not actively in use by processes, the system and the system cache. This memory needs to be written out before it will be available for allocation to a process or for system use.

Cache pages on the modified list have been altered in memory. No process has specifically asked for this data to be in memory, it is merely there as a consequence of caching. Therefore it can be written to disk at any time (not to the page file, but to its original file location) and reused. However, since this involves I/O, it is not considered to be Available physical memory.

Standby memory

Indicates the amount of memory assigned to the standby list.  

MB

This memory contains cached data and code that is not actively in use by processes, the system and the system cache. It is immediately available for allocation to a process or for system use. If the system runs out of available free and zero memory, memory on lower priority standby cache page lists will be repurposed before memory on higher priority standby cache page lists.

Typically, Standby memory is the aggregate of Standby Cache Core Bytes,Standby Cache Normal Priority Bytes, and Standby Cache Reserve Bytes. Standby Cache Core Bytes is the amount of physical memory, that is assigned to the core standby cache page lists. Standby Cache Normal Priority Bytes is the amount of physical memory, that is assigned to the normal priority standby cache page lists. Standby Cache Reserve Bytes is the amount of physical memory, that is assigned to the reserve standby cache page lists.

Cached memory

Indicates an aggregate of Standby memory and Modified memory.

MB

 

Maximum memory allocated

Indicates the maximum amount of memory allocated to this VM.

MB

 

Memory usage by maximum allocated memory

Indicates the percentage of memory utilized from the maximum amount of memory allocated to this VM.

Percent

 

Automatic action status

Indicates the current status of automatic action.

 

The values that this measure can report and their corresponding numeric values are discussed in the table above:

Measure value Numeric value
Not Required 1
Started 2
Running 3
Completed 4
Not Enabled 5
Failed 6

Note:

By default, this measure reports the Measure Values listed in the table above. In the graph of this measure however, the value of this measure is represented using their numeric equivalents only.

Use the detailed diagnosis of this measure to find out what are the automation actions triggered when the memory utilization exceeds the value specified against the Automation Memory Limit parameter.