Citrix XenApp Troubleshooting Scenarios Interview Questions

This blog covers the commonly asked Citrix XenApp Troubleshooting Scenarios during Interviews. The previous blogs discuss the XenApp Installation and Components Questions.

What happens if datastore connectivity is lost?

If the server loses its connection to the central data store, there’s no limit to how long it will continue to function. (In MetaFrame XP, this is limited to 48 or 96 hours, but that was because the data store also store license information.) But today, the server can run forever from the LHC and won’t even skip a beat if the central connection is lost. In fact now you can even reboot the server when the central data store is down, and the IMA service will start from the LHC without any problem. (Older versions of MetaFrame required a registry modification to start the IMA service from the LHC.)

What will you check when any user is not able to launch Citrix application?

• First try to launch same application from Citrix server (on which you installed and published)
• Try to add same application to your ID and try to launch from administrator machine
• Verify that latest Citrix client software/receiver version installed at desktop
• Verify that user is having correct proxy settings to connect to  Citrix network (for remote users)

• Check user permissions for that Applications
• Verify any policies are applied on the particular application or groups.

What will happen if LHC in Citrix corrupted?

If LHC is corrupted, the server communication with the datastore would be affected; as a result, server will not be able to handle user requests for applications; IMA service would fail to start and you will have recreate LHC

You cannot access application from that server.

IMA will not start

Recreating LHC will fix the issue.

How do you repair the IMA local host cache?

The data store server must be available for dsmaint recreatelhc to work. If the data store is not available, the IMA service cannot start.

• Stop the IMA service on the XenApp server, if it is started. This can be done using the command: net stop IMA service, or from services.
• Run dsmaint recreatelhc, which renames the existing LHC database, creates a new database, and modifies the following registry key HKEY_LOCAL_MACHINESOFTWARE Citrix IMA Runtime PSRequired key to 1. Setting the value PSRequired to 1 forces the server to establish communication with the data store in order to populate the Local Host Cache database. When the IMA service is restarted, the LHC is recreated with the current data from the data store.
• Restart the IMA service. This can be done via the command line, net start IMA service, or from services.

How to recover from IMA failing?

There are many reasons that the IMA Service doesn’t start

1. IMA Service load time
2. IMA Service subsystem
3. Missing Temp directory
4. Print spooler service
5. ODBC configuration
6. Roaming Profile

Check the Windows Registry setting: HKEY_LOCAL_MACHINESOFTWARECitrixIMARuntimeCurrentlyLoadingPlugin
If there is no value specified in the CurrentlyLoadingPlugin portion of the above Windows Registry entry then the IMA Service could not connect to the data store or the local host cache is missing or corrupt.
If a CurrentlyLoadingPlugin value is specified the IMA Service made a connection to the data store and the value displayed is the name of the IMA Service subsystem that failed to load.
If administrators see an “IMA Service Failed” error message with an error code of 2147483649 when starting the Presentation Server the local system account might be missing a Temp directory which is required for the IMA Service to run.
Change the IMA Service startup account to the local administrator and restart the server. If the IMA Service is successful in starting under the local administrator account then it is likely that a missing Temp directory for the local system account is causing the problem.
If the Temp directory is not present then manually create one as >Temp. For example: C:\Windows\Temp
Also verify that the TMP and TEMP system environment variables point to the temporary directory. Restart the server to restart the IMA Service

How to change the port number for XML service?

CTXXMLSS.EXE to change the port number.

How to change the port used by XML service?

By default XML service uses port 80. But citrix recommends using port 8080 inorder to avoid conflicts with IIS.

To change the port used by XML service:

In XenApp 6 and above – this can be changed via Citrix policies.

In Earlier versions – Use the ctxxmlss command-line utility. This can be done by unloading the Citrix XML Service with /u, changing the port with /r<port number> and restarting the XML service.

ctxxmlss /u

ctxxmlss /r8080

An alternative method is by changing the port in the registry (and restart the Citrix XML service after changing).

Key :HKLM\System\CurrentControlSet\Services\CtxHTTP

Value: TCP Port

The value is listed in hex, you need to change the view to decimal.

How will you remove Citrix server from the farm?

If the server is unresponsive, remove it by right click on server in the console. For functional server, remove it from add/remove programs. use CHFARM command

If any user gets error that Resources is unavailable in Citrix than what will you do?

• Check the application server is function correctly
• Communicate with License Server not broken
• Check for IMA service

Users are experiencing issues when attempting to connect to published resources through Access Gateway. Where you are going to monitor or checking the settings?

Citrix XTE Service and Citrix IMA Networking

How to recover Citrix License Server? Or what will happen when license server goes down?
The Citrix servers can function without contacting the license server and it is 30-days fault tolerant, and in Enterprise version an alert can be set with Resource Manager to send an email in case of License Server Connection Failure. If the license server reconnects at any time in the thirty days the problem resolves itself. If the server is not going to come back up, then the license file, digitally signed with the case-sensitive hostname of the old license server, is the critical component. The license file, a *.lic file, can be backed up to a thumb drive separately, and restored to a new server with the same name of the old license server, and the Citrix License server software installed.

How do you troubleshoot printing issues?

• Check print spooler service
• Check printer mapping errors in event log
• Check printer driver availability n compatibility
• Check printer policies for over rides

For example you have a xenapp server citrixxa1, how you are going to check server load for this XenApp server?

Query farm citrixxa1 /load

If you want to configure printing in an environment to make network printers automatically appear to all users without any setup. Which policy you are going to apply it?

We have to configure Session printers through the citrix policies

One of the users from sales department is directly complaining to TL about CRM application is taking too long to launch the application and then TL said to you check it and resolve it, what is the best possible solution you can able to do it?

Configuring pre-launch sessions for users in the sales department