VM Details – Xen Test

This test monitors the amount of the physical server's resources that each guest on an Citrix Hypervisor is taking up. Using the metrics reported by this test, administrators can determine which virtual guest is taking up most CPU, which guest is generating the most network traffic, which guest is taking up the maximum memory utilization, which guest has the maximum disk activity, etc. Note that the amount of resources taken up by a virtual guest will be limited by the resource allocations that have been made by administrators. For example, an administrator could cap the amount of memory that a specific guest may take. Also, virtual guests can be organized into resource pools, and allocation of resources can be made at the resource-pool level. In this case, virtual guests allocated to the same resource pool contend for the resources allocated to the resource pool.

Target of the test : A Citrix Hypervisor host

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for each guest configured on the target hypervisor host

Configurable parameters for the test
Parameter Description

Test period

How often should the test be executed.

Host

The host for which the test is to be configured.
Port

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

Xen User, Xen Password and Confirm Password

To enable the eG agent to connect to the XenServer API for collecting statistics of interest, this test should login to the target hypervisor as a root user. Provide the name of the root user in the Xen User text box. Root user privileges are mandatory when monitoring a XenServer 5.5 (or below). However, if you are monitoring XenServer 5.6 (or above) and you prefer not to expose the credentials of the root user, then, you have the option of configuring a user with pool-admin privileges as the Xen User. If you do not want to expose the credentials of a root/pool-admin user, then you can configure the tests with the credentials of a Xen User with Read-only privileges to the XenServer. However, if this is done, then the Xen Uptime test will not run, and the Xen CPU and Xen Memory tests will not be able to report metrics for the control domain descriptor. To avoid such an outcome, do the following before attempting to configure the eG tests with a Xen User who has Read-only privileges to the Citrix Hypervisor:

  • Modify the target hypervisor's configuration in the eG Enterprise. For this, follow the Infrastructure -> Components -> Add/Modify menu sequence, pick Citrix Hypervisor as the Component type, and click the Modify button corresponding to the target hypervisor.
  • In the MODIFY COMPONENT DETAILS page that then appears, make sure that the os is set to Xen and the Mode is set to SSH.
  • Then, in the same page, proceed to provide the User and Password of a user who has the right to connect to the XenServer console via SSH.
  • Then, click the Update button to save the changes.

Once this is done, you can configure the eG tests with the credentials of a Xen User with Read-only privileges.

The password of the specified Xen User needs to be mentioned in the Xen Password text box.

Then, confirm the Xen Password by retyping it in the Confirm Password text box.
SSL

By default, the Citrix Hypervisor is not SSL-enabled. This indicates that by default, the eG agent communicates with the target hypervisor using HTTP. Accordingly, the SSL flag is set to No by default. If you configure the target hypervisor to use SSL, then make sure that the SSL flag is set to Yes, so that the eG agent communicates with the target hypervisor using HTTPS. Note that a default SSL certificate comes bundled with every Citrix Hypervisor installation. If you want the eG agent to use this default certificate for communicating with an SSL-enabled Citrix Hypervisor, then no additional configuration is required. However, if you do not want to use the default certificate, then you can generate a self-signed certificate for use by the target hypervisor. In such a case, you need to explicitly follow the broad steps given below to enable the eG agent to communicate with the target hypervisor via HTTPS:

  • Obtain the server-certificate for the Citrix Hypervisor
  • Import the server-certificate into the local certificate store of the eG agent

For a detailed discussion on each of these steps, refer to the Troubleshooting section of this document.

Inside View Using

By default, this test obtains the “inside view” of VMs using the eG VM Agent. Accordingly, the Inside view using flag is set to eG VM Agent by default. The eG VM Agent is a piece of software, which should be installed on every VM on a hypervisor. Every time the eG agent runs this test, it uses the eG VM Agent to pull relevant 'inside view' metrics from each VM. Once the metrics are collected, the eG agent then communicates with each VM agent and pulls these metrics, without requiring administrator privileges. Refer to Configuring the Remote Agent to Obtain the Inside View of VMs for more details on the eG VM Agent.

Domain, Admin User, and Admin Password, and Confirm Password

By default, these parameters are set to none. This is because, by default, the eG agent collects 'inside view' metrics using the eG VM agent on each VM. Domain administrator privileges need not be granted to the eG agent if it uses this default approach to obtain the 'inside view' of Windows VMs.

Ignore VMs Inside View

Administrators of some high security XenServer 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, your IGNORE 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 Citrix Hypervisor host 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 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.

Ignore Winnt

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

Aggregate User Sessions

This flag is closely related to the REPORT BY USER flag. Since the REPORT BY USER flag is set to No by default for a Citrix hypervisor, this test will, by default, ignore the status of the AGGREGATE USER SESSIONS flag while monitoring that server. In case of the Citrix hypervisor - VDI on the other hand, the REPORT BY USER flag is set to Yes by default. Therefore, the status of the AGGREGATE USER SESSIONS flag gains significance in the case of this model. By default, the AGGREGATE USER SESSIONS flag is set to No. This implies that if a single user is currently logged into multiple guests, then this test, by default, will report a set of measures for every username on guestname. On the other hand, if the status of this flag is changed to Yes, then, this test will report a set of (aggregated) measures for every distinct user to the virtual desktop environment. In other words, this test will report measures that are aggregated across all the currently active sessions for a user, spanning multiple VMs.

Webport

By default, in most virtualized environments, the target hypervisor listens on port 80 (if not SSL-enabled) or on port 443 (if SSL-enabled). This implies that while monitoring an SSL-enabled Citrix hypervisor, the eG agent, by default, connects to port 443 of the server to pull out metrics, and while monitoring a non-SSL-enabled Citrix hypervisor, the eG agent connects to port 80. Accordingly, the webport parameter is set to 80 or 443 depending upon the status of the ssl flag.  In some environments however, the default ports 80 or 443 might not apply. In such a case, against the webport parameter, you can specify the exact port at which the target hypervisor in your environment listens so that the eG agent communicates with that port.

Report by User

While monitoring a Citrix hypervisor, the REPORT BY USER flag is set to No by default, indicating that by default, the guest operating systems on the target hypervisor are identified using the host name specified in the operating system. On the other hand, while monitoring a Citrix hypervisor-VDI, this flag is set to Yes by default; this implies that in case of the Citrix hypervisor-VDI model, by default, the desktops will be identified using the login of the user who is accessing them. 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 the report powered os 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.

Report Powered ON

You can set the REPORT POWERED ON status to Yes, so that the test reports an additional measure, Is VM powered on?, revealing whether a guest OS is currently running or not. The default status of this flag is set to Yes for a Citrix hypervisor. For a Citrix Hypervisor – VDI component on the other hand, this flag is set to No by default. This is because, in such environments, the virtual desktops will be in the powered-off state most of the time.

Detailed Diagnosis

  1. To make diagnosis more efficient and accurate, the eG suite 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

Is VM powered on? :

Whether the virtual machine is currently running on the XenServer host or no.

 

While the test reports a wide variety of other metrics too for virtual machines that are alive, only the powered on status is indicated for virtual machines that are currently not available.

The value Yes for this measure indicates that the guest is up and running. The value No could indicate that the guest has been powered-off; it could also indicate that XenMotion has moved the guest to a different server.

The numeric values that correspond to each of the powered-on states discussed above are listed in the table below:

State Value
Yes 1
No 0

Note:

By default, this measure reports Yes or No to indicate VM status. The graph of this measure however, represents the status of a VM using the numeric equivalents - 0 or 1.

Physical CPU usage:

Indicates the percentage of physical CPU used by the guest.

Percent

A high value for this measure indicates a virtual machine that is using a lot of the processor - possibly because one or more processes on this VM are taking a lot of CPU.

Free physical memory:

Indicates the amount of memory available for use with the guest.

 

MB

Ideally, this value should be high. A low or consistent decrease in this value denotes that the application(s) executing on the guest are consuming memory excessively. You might want to consider increasing the memory allocated to the guest. XenServer Enterprise and XenServer Standard allow that a Linux/Windows VM can use up to 32GB of memory. Moreover, Xen has implemented a balloon driver concept for each domain, enabled independently, that allows the operating system to adjust its current memory allocation up to the maximum limit configured. This allows “unused” allocation to be consumed in other areas, potentially allowing for stable over-commitment of memory resources. Because of this constantly changing memory allocation, memory is allocated and freed dynamically at a granularity of the page-level.

Total physical memory allocated:

Indicates the amount of physical memory currently allocated to the guest.

MB

 

Used physical memory:

Indicates the amount of memory used by the guest.

MB

 

Usage of allocated memory:

Indicates the percentage of allocated memory that is being used by the guest.

Percent

High memory consumption over long periods can deplete the free memory on the guest, causing prolonged delays in the execution of the application(s) hosted by the guests.

Disk capacity:

Indicates the total allocated disk space of the guest.

MB

 

Disk read rate:

Indicates the rate at which the guest read from the disk.

Kbytes/Sec

 

Disk write rate:

Indicates the rate at which the guest wrote data to the disk.

Kbytes/Sec

 

Network data received:

Indicates the network I/O reads performed by the guest.

Mbps

 

Network data transmitted:

Indicates the network I/O writes performed by the guest.

Mbps

 

Virtual CPU utilization:

Indicates the percentage of allocated CPU resources that this VM is currently using.

Percent

Comparing the value of this measure across VMs will enable you to accurately identify the VMs on which CPU-intensive applications are executing. 

Virtual CPUs:

Indicates the number of virtual CPU cores allocated to this VM.

Number

 

Disk read and write rate:

Indicates the rate at which read-write requests were processed by this VM.

Kbytes/Sec

Compare the value of this measure across VMs to know on which VM I/O activity was abnormally high.

Network data sent and received:

Indicates the rate at which network I/O is processed by this VM.

Mbps

Compare the value of this measure across VMs to know on which VM network I/O activity was abnormally high.

Total IOPS:

Indicates the rate at which I/O operations are performed by this VM.

Requests/Sec

This measure is a good indicator of the I/O processing capacity of the VM.  A high value is hence desired for this measure. A consistent drop in this value could indicate a processing bottleneck. In such a situation, you can compare the value of the Read operations and Write operations measures of the corresponding VM to figure out where the bottleneck lies – in reading data from the VM? or in writing to the VM?

Read operations:

Indicates the rate at which this VM services read requests.

Requests/Sec

Ideally, the value of this measure should be high. A steady drop in this value indicates a slowdown in processing read requests. Compare the value of this measure across VMs to know which VM is the slowest in responding to read requests.

Write operations:

Indicates the rate at which this VM services write requests.

Requests/Sec

Ideally, the value of this measure should be high. A steady drop in this value indicates a slowdown in processing write requests. Compare the value of this measure across VMs to know which VM is the slowest in responding to write requests. 

Time spent waiting for I/O:

Indicates the percentage of time the host’s CPU was waiting for this VM to complete I/O processing.

Percent

A high value for this measure indicates that the VM is taking too long to complete I/O processing. This hints at a probable processing bottleneck with the VM. 

Average queue size:

Indicates the average number of I/O requests to this VM that are in queue for processing.

Number

If the value of this measure grows consistently, it indicates that the VM is unable to process requests quickly enough to clear the queue. The VM with the maximum number of queued requests could be experiencing a serious I/O processing bottleneck. To identify this VM, compare the value of this measure across VMs.

Current requests in flight:

Indicates the number of I/O requests to this VM that are currently being processed. 

Number

 

Current sessions:

This measure is relevant only for monitoring of virtual desktops (i.e., for Citrix XenServer - VDI servers). When reporting metrics for specific users, this metric indicates the number of sessions that each user has currently logged into; this measure will be available only if the test reports measures per currently logged in user.

Number

This is a good indicator of how busy the user is. The detailed diagnosis of this measure, if enabled, reveals the guests to which the user is currently logged on to.

Virtual CPUs full run:

Indicates the percentage of the time that the vCPUs were running on this VM.

Percentage

A high value for this measure indicates that the vCPUs are using a lot of the physical CPU resources for prolonged duration.

Virtual CPUs partial run:

Indicates the percentage of time that some of the total vCPUs were running, and others were blocked on this VM.

Percentage

  

Virtual CPUs idle:

Indicates the percentage of time that the vCPUs were blocked or offline on this VM.

Percentage

  

Virtual CPUs concurrency hazard:

Indicates the percentage of time that some of the total vCPUs were running, and other vCPUs were waiting for the physical CPU.

Percentage

  

Virtual CPUs full contention:

Indicates the percentage of time that the vCPUs on this VM were waiting for the physical CPU.

Percentage

  

Virtual CPUs partial contention:

Indicates the percentage of time that some of the total vCPUs were waiting for the physical CPU, and others were blocked.

Percentage