Personal vDisk – OS Test

The personal vDisk retains the single image management of pooled and streamed desktops while allowing people to install applications and change their desktop settings.

Unlike traditional Virtual Desktop Infrastructure (VDI) deployments involving pooled desktops, where users lose their customizations and personal applications when the administrator alters the base virtual machine (VM), deployments using personal vDisks retain those changes. This means administrators can easily and centrally manage their base VMs while providing users with a customized and personalized desktop experience.

Personal vDisks provide this separation by redirecting all changes made on the user's VM to a separate disk (the personal vDisk) attached to the user's VM. The content of the personal vDisk is blended at runtime with the content from the base VM to provide a unified experience. In this way, users can still access applications provisioned by their administrator in the base VM.

But, what happens if a personal vDisk runs out of space? Simple! Users will no longer be able to hold on to their customizations, allowing them access to only the base VM and the applications installed therein! This outcome beats the entire purpose of having personal vDisks! If this is to be avoided, then administrators should continuously monitor the usage of the personal vDisks, proactively detect a potential space crunch, determine what is causing the rapid erosion of space on the personal vDisk, and fix the root-cause, before desktop users complain. This is where the Personal vDisk – OS test helps.

For each VM on a itrix hypervisor, this test tracks the status and space usage of its personal vDisk and promptly reports errors / abnormal space usage. This way, administrators can accurately identify personal vDisks with very limited space, which VM such personal vDisks are associated with, and what is consuming too much disk space – user profiles? Or user applications?

Target of the test : A Citrix Hypervisor

Agent deploying the test : An internal/remote agent

Outputs of the test : One set of results for every user_on_VM

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.
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.
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.
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	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

Personal vDisk service status

Indicates whether Citrix Personal vDisk service is running or not on this VM.

The values that this measure can report and their corresponding numeric values have been discussed in the table below:

Measure Value	Numeric Value
Stopped	0
Running	1
Not installed	2

Note:

By default, this test reports the Measures Values listed in the table above to indicate the status of the Personal vDisk service. In the graph of this measure however, the same will be represented using the numeric equivalents.

Recompose status

Indicates the status of the initially provisioned disk or the updated image.

Number

Use the detailed diagnosis of this measure to know for which VM the initial personal vDisk provisioning or image update were unsuccessful and why. The VM can be in one of the following states:

OK – The initial provisioning or last image update was successful.
Disk Init – This is the first time that the personal vDisk has started or been resized. It is being initialized and partitioned by the service.
Disk Format – The personal vDisk is being formatted.
Updating – The initial provisioning or an image update is in progress.
Error (Disk Discovery) – An error state. An error occurred while discovering the personal vDisk.
Error (Disk Init) – An error state. An error occurred while partitioning or formatting the personal vDisk.
Error (Sys Init) – An error state. An error occurred while starting the Personal vDisk Service or configuring the personal vDisk.
Error (Update) – An error state. An error occurred during the initial provisioning or the last image update.
Unknown – An error state. An error occurred but the cause is unknown.

Space used by user applications

Indicates the amount of space used by applications installed on the personal vDisk attached to this VM.

Personal vDisks have two parts, which use different drive letters and are by default equally sized.

One part comprises a Virtual Hard Disk file (a .vhd file). This contains items such as applications installed in C:\Program Files. By default, this part uses drive V: but is hidden from users.

These measures indicate how much space has been allocated to this .vhd file and how much of the allocated space has been utilized by user applications contained in this file.

A high value for the Space used by user applications and Space utilized by user applications measures is indicative of excessive space used by user applications. You can compare the value of these measures across VMs to know which user to which VM has utilized too much space reserved for user applications on the personal vDisk. If the value of the Space utilized by user applications measure grows close to 100% for any VM, it implies that potentially, the user to that VM will not be able to install any applications on the personal vDisk; nor access any applications.

Space allocated for user applications

Indicates the amount of space allocation for storing user applications on the personal vDisk attached to this VM.

Space utilized by user applications

Indicates the percentage of allocated space used by applications installed on the personal vDisk attached to this VM.

Percent

Space used by user profiles

Indicates the amount of space used for storing user profiles on the personal vDisk attached to this VM.

Personal vDisks have two parts, which use different drive letters and are by default equally sized.

One part comprises C:\Users (in Windows 7) or C:\Documents and Settings (in Windows XP). This contains user data, documents, and the user profile. By default this uses drive P:.

These measures indicate how much space has been allocated to user profiles and how much of the allocated space has been utilized by user profiles.

A high value for the Space used by user profiles and Space utilized by user profiles measures is indicative of excessive space used by user profiles. You can compare the value of these measures across VMs to know which VM’s user profiles are consuming the maximum space on the personal vDisk. If the value of the Space utilized by user profiles measure grows close to 100% for any VM, it implies that potentially, the user to that VM will not be able to store/access any more documents or user data on the personal vDisk .

Space allocated for user profiles

Indicates the amount of space allocated for storing user profiles on the personal vDisk attached to this VM.

Space utilized by user profiles

Indicates the percentage of allocated space that has been used up by user profiles on the personal vDisk attached to this VM.

Percent

Free space

Indicates the amount of unused space on the personal vDisk attached to this VM.

Ideally, the value of this measure should be high. You can compare the value of this measure across VMs to know which VM’s personal vDisk has the least free space. You may then want to resize that personal vDisk to accommodate more data.

Total size

Indicates the total size of the personal vDisk attached to this VM.

The minimum size of a Personal vDisk is 3 GB, however a size of 10 GB is recommended.

Space utilized

Indicates the percentage of space in the personal vDisk attached to this VM that is currently used.

Percent

A consistent increase in the value of this measure is a cause for concern, as it indicates a gradual erosion of free space in the personal vDisk of a VM.

By comparing the value of this measure across VMs, you can identify which VM’s personal vDisk is running out of space! Once the VM with the space-hungry vDisk is isolated, you may want to compare the value of the Space utilized by user applications and Space utilized by user profiles measures of that VM, to clearly understand what is occupying too much space in the personal vDisk – is it the user profiles? Or is it the user applications? Based on this inference, you can figure out which drive partition of the personal vDisk has limited free space, and can decide between freeing up space in that partition or allocating more space to the personal vDisk itself.