Xen XAPI Memory Test

XAPI – short for Xen API - is at the heart of the Citrix XenServer. It manages everything - all the resources in your XenServer environment. It reads in configs, initializes networking paths, checks licensing, maintains a database with all this info (the XAPI database), manages Storage Repositories, manages VMs, tracks VM states, manages networking, High Availability and other XenServer hosts in the pool and more. In short, every XenServer request or action is done via XAPI.

For performing all these operations, the XAPI daemon uses the memory allocated. If users to the XenServer or its VMs complain of slowdowns, it would be wise to check the memory usage of the XAPI daemon as well, amongst other things, as significant memory usage by the XAPI can also cause the host and VMs to choke. To enable administrators to track the memory usage of the XAPI daemon, the eG agent periodically runs the Xen XAPI Memory test. This test checks the memory usage of the XAPI daemon at configured intervals, captures abnormal usage patterns (if any), and proactively alerts administrators to them, so that potential slowdowns in the performance of the XenServer can be averted.

Target of the test : A XenServer host

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for each local SR on the monitored XenServer host

Configurable parameters for the test

  1. Test period - How often should the test be executed
  2. Host - The host for which the test is to be configured.
  3. XEN user - To enable the eG agent to connect to the XenServer API for collecting statistics of interest, this test should login to the XenServer 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 XenServer:

    • Modify the target XenServer’s configuration in the eG Enterprise system. For this, follow the Infrastructure -> Components -> Add/Modify menu sequence, pick Citrix XenServer as the Component type, and click the Modify button corresponding to the target XenServer.
    • 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.
  4. Once this is done, you can configure the eG tests with the credentials of a xen user with Read-only privileges.   

  5. xen password - The password of the specified xen user needs to be mentioned here.
  6. confirm password - Confirm the xen password by retyping it here.
  7. ssl - By default, the Xen Server is not SSL-enabled. This indicates that by default, the eG agent communicates with the XenServer using HTTP. Accordingly, the ssl flag is set to No by default. If you configure the XenServer to use SSL, then make sure that the SSL flag is set to Yes, so that the eG agent communicates with the XenServer using HTTPS. Note that a default SSL certificate comes bundled with every XenServer installation. If you want the eG agent to use this default certificate for communicating with an SSL-enabled XenServer, 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 XenServer. In such a case, you need to explicitly follow the broad steps given below to enable the eG agent to communicate with the XenServer via HTTPS:

    • Obtain the server-certificate for the XenServer
    • 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.

  8. webport - By default, in most virtualized environments, the XenServer listens on port 80 (if not SSL-enabled) or on port 443 (if SSL-enabled). This implies that while monitoring an SSL-enabled XenServer, the eG agent, by default, connects to port 443 of the server to pull out metrics, and while monitoring a non-SSL-enabled XenServer, 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 XenServer in your environment listens so that the eG agent communicates with that port.


Measurements made by the test

Measurement Description Measurement Unit Interpretation

Memory usage:

Indicates the amount of allocated memory that is used by the XAPI daemon.


A low value is desired for this measure.

Free memory:

Indicates the amount of allocated memory that is still unused by the XAPI daemon.


Ideally, the value of this measure should be high. A consistent decrease in this value could indicate excessive memory usage by the XAPI.

Live memory:

Indicates the amount of live memory that is used by the XAPI.



Memory allocation:

Indicates the amount of memory allocated by the XAPI daemon.