How To Put Citrix Servers Out Of Citrix Load

So a couple weeks ago I had been asked by my colleague to put some of my servers out of load for maintenance. Then I was like,  "okay, just disable logon then!". Then, he made some weird face to me while saying "Fool, if you disable logon, how am I suppose to login, then? I don't want to trouble myself with console... go figure it out!".. aaaaaannd yes, I figured it out (or was I?? :D)

Description :
Put Citrix servers out of Citrix load (some sort of private mode / maintenance mode).



How To Do :

1. From the Citrix server (or from your local machine of you has it installed), launch XenApp Advanced Configuration Console.
   
   
   
2. Right click at Load Evaluator, and click at New Load Evaluator.
   
   
   
3.  You will see this screen. Put a name of your Load Evaluator (ie. Out of Loads), and at the Available Rules section, click at Scheduling.
   
   
   
4.  Add Scheduling Rule (you will see it moved from left section to right.
   
   
   
5.  Now, at every single day, press Remove Interval.
   
   
   
6.  This is the outcomes. Press OK.
   
   
   
7. Now you will see another Load Evaluator created.
   
   
   
8. From Citrix Delivery Console, right click at desired server, go to All Tasks > and choose Assign load evaluator.
   
   
   
9. Change current Load Evaluator to the newly created Load Evaluator.
   
   
   
10.  Press OK.
    
    
    
11.  Now, whenever users want to access applications resides in that server, users will see this. Therefore, it is best to configured other servers to host the applications, so it won't interrupt users' experiences.
    

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CHFARM Failed on Windows Server 2008

I got this issue when I want to perform change farm on one of my Citrix XenApp farms. The installed version is Citrix XenApp 5 for Server 2008. I have not encountered any issue before while using Windows Server 2003, so I believe this issue is somehow related to the differences between those 2 Windows versions, well, particularly the UAC. 

Issues :

• CHFARM utility failed in the middle, with below error :
  

Troubleshooting 

• It is due to UAC permission, it blocks CHFARM utility from properly running because it ran in Admin Approval Mode.

Resolution :

1. Go to Start > run, and type secpol.msc
   
   
   
    
2.  When you see this UAC permission control screen, choose I want to complete this action option, and press Ctrl + Alt + End as requested after that.
   
   
   
   
   
   
3.  Press Continue 
   
   
   
4.  Browse to Security Options as below
   
   
   
5.  Search for this option :

   

   User Account Control : Rul all administrators in Admin Approval Mode

   
   
6.  Right click at the option, and choose Properties
   
7. At here, choose Disabled,press Apply and OK
   
   
   
8. Below screen will explain why on this setting. Once everything is good, press Apply and OK.
   

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Enable or Disable Logon for Citrix XenApp Servers via Citrix Console

After we talked on how to disable logon using command, this post will show on how to disable logon using Citrix Console.

Note that :-

• Users are not able to remote to the server, no RDP, no ICA, nothing.
• Once logon disabled, users only able access the server via virtualization Console like VMware Client or XenCenter (Virtual server). For physical server, it is either physically sitting before the server, KVM or Remote Access Card (DRAC, or HP iLO)
• For Command Line, it only can be used locally. I haven't try using PSTOOL yet, but I will update this post whether I can access the server using PSTOOL after logon disabled.
• For GUI, as we will use Citrix Console, hence it can be done remotely from other Citrix XenApp servers, within the same farm. Hence, if the farm only has one Citrix XenApp server, then you need to get in the box via physically there or virtualization client.

Description

• Disable / enable logon for Citrix XenApp servers via Command Line.

How To Do :

1.  From Citrix Console, you can easily spot whether the server is having the session login disabled, or enabled. If it shows Disable Logon, it means current status is Enabled, and vice versa.

   

   Currently Disabled

   
   
   

   

   
   

   Currently Enabled

   
   
   
2. To disable logon, from Citrix Console, right click at the server name, go to All Tasks, and choose Disable logon.
   
   
   
   
   
   
3.  Hence, when users try to RDP the server, they will see this. For ICA connections, this server will not be used. If one published application was published only to that server, then users will not be able to access that application.
   
   
   
   
   
   
4. To enable the logon back, from Citrix Console, right click at the server name, go to All Tasks, and choose Enable logon.
   

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Enable or Disable Logon for Citrix XenApp Servers via Command Line

Well, as a Citrix Admin, you are able to prevent any users from accessing your Citrix XenApp servers, especially when the server is under maintenance mode, or you purposely want to put the server out-of-loads. there are 2 ways to do this; GUI or command. 

But bear in mind that :-

• Users are not able to remote to the server, no RDP, no ICA, nothing.
• Once logon disabled, users only able access the server via virtualization Console like VMware Client or XenCenter (Virtual server). For physical server, it is either physically sitting before the server, KVM or Remote Access Card (DRAC, or HP iLO)
• For Command Line, it only can be used locally. I haven't try using PSTOOL yet, but I will update this post whether I can access the server using PSTOOL after logon disabled.
• For GUI, as we will use Citrix Console, hence it can be done remotely from other Citrix XenApp servers, within the same farm. Hence, if the farm only has one Citrix XenApp server, then you need to get in the box via physically there or virtualization client.

Description

• Disable / enable logon for Citrix XenApp servers via Command Line.

How To Do :

1. RDP to the Citrix XenApp server, and open Command prompt. firstly, you may want to type Change Logon in order to know what commands can be used.
   
   
   These are commands that can be used :
   CHANGE LOGON {/QUERY | /ENABLE | /DISABLE)
   /QUERY     Query current session login mode
   /ENABLE    Enable user login from sessions
   /DISABLE   Disable user login from sessions
   

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What Is Local Host Cache?

In previous post I wrote about what will happen if the Citrix XenApp farm lost connection with its datastore. Well, because of Local Host Cache, users will still be able to access the applications without too much issue. But, what is Local Host Cache (LHC)?

LHC is like a mini-DB of the farm, and created on all Citrix XenApp servers. Why I said mini-DB? It is because it contains a portion (subset) of Data Store information. 


There are 4 main information stored in the LHC :

• All servers in the farm, and their basic information.
• All applications published within the farm and their properties.
• All Windows network domain trust relationships within the farm.
• All information specific to itself. (Product code, SNMP settings, licensing information)

There are 2 primary functions of LHC :

• Redundancy - a Citrix XenApp still function as normal if connection to datastore losts.
• Performance - LHC cache information used by ICA clients for enumeration and application resolution. By having this, a faster response to ICA client request is provided, as the server does not need to contact other member servers about published applications.

LHC info is stored in Imalhc.mdb (an Access database). By default, it is stored in %ProgramFiles%\Citrix\Independent Management Architecture folder.

IMA service is heavily related to LHC. IMA service is responsible to get LHC synchronzied with the data store. Hence, restarting IMA service during DB server outage will cause the service can't be started.



Reference :

• http://careerride.com/view.aspx?id=2774
• http://support.citrix.com/article/CTX759510

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Change Farm Utility ( CHFARM) Has Stopped Working

Well, this issue was occurred to me last weekend, when I was busying myself changing my Citrix XenApp servers from farm A to farm B, using GUI. Why? because I have nothing to do (on weekend? seriously??). Please put my forever alone life aside, shall we? Well, this issue occurred to my XenApp 5 for Server 2008 farm. Hmm, Server 2008 is the keyword there... :)

Issues :

• Citrix Admins received below screen after putting the credential for ODBC Driver Access.
  
• Citrix Admins can't move forward, as the GIU will froze just after putting the credential.
  

Troubleshooting 

1. Go to Start > Run, and type SecPol.msc
   
   
    
2. You will be prompted with all UAC permission, so just proceed accordingly

   

   Click at I want to complete this task

   
   

   

   Press Ctrl + Alt + End

   

   Press Continue

   
   
   
3. After that, you will see this console. Our focus is on Security Settings > Local Policies > Security Options
   
   
   
4. On the right column, find this configuration, and check the setting configured
   

Resolution :

• Right click at the configuration item, and choose Properties
  
  
• From this box, change the option from Enabled to Disabled
  
  

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What Happen If My XenApp Farm Cant Connect to the Citrix License Server?

Okay this is interesting. In my previous post, I said some candidates did not manage to get the answer correct. But for this question, they got all correct! they even mentioned how many hours rather than how many days. ( how they maange to calculate that fast? Did they have calculator in hand? ahh! smartphones!)

Again, back to the real business. if it happens that the Citrix farm lost connectivity with Citrix license, users still be able to launch the Citrix published application. However, there is 30 days / 720 hours grace period. After this grace period, users won't be able to launch any Citrix published applications.

Question... If my Citrix XenApp servers lost connections to DataStore, I can't reboot my Citrix XenApp servers. But what if the servers lost connections to Citrix License server? The answer is, no problem! it will not give any impact on the grace period or Citrix functionality within grace period. The information stored  in mps-wsxica_mps-wsxica.ini, thus rebooting Citrix servers won't delete the file.



Reference : 

• http://www.brianmadden.com/forums/t/12780.aspx
• http://www.brianmadden.com/blogs/brianmadden/archive/2007/06/04/how-does-a-citrix-presentation-server-know-what-licenses-you-have-when-it-loses-connectivity-to-the-license-server.aspx

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What Happen If My XenApp Farm Cant Connect to the Data Store?

This is one of my favorite interview question, I just don't know why. it seems simple, but some candidates failed to give a proper answer (poor them). I wish all of them better luck next time.

Okay, now back to the real business. From Citrix Administrators Point-of-View, losing a DB may cost chaos, depending on how severe the issue is. However, from user perspective, nothing is different. Users wont really impacted of this. They still be able to launch Citrix published applications and works as normal. Thanks to Local Host Cache (LHC), it eases the burden of Citrix Admins (oh really?)

However, although all Citrix XenApp servers have LHC, there are some conditions that Citrix Admins need to remember :

• There is no grace period for this (MPS 3.0 and above). Users still be able to connect to the Citrix farm (lucky!)
• Only static information  available to users. No new info can be added and current info cannot be changed (not really...)

In any circumstances, DO NOT :

• Restart / reboot the Citrix XenApp servers. it will cause the server to contact DB server. This will result IMA service won't started.
• Restart IMA service (same reason as above).
• Re-create LHC (in order to re-create LHC, we need to stop IMA service).

Reference :

• http://citware.blogspot.com/2012/05/if-you-loose-connectivity-to-data-store.html
• http://citrixsolutions.blogspot.com/2009/04/all-about-local-host-cache.html
• http://support.citrix.com/article/CTX105763

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Error on Citrix Web Interface - Credential Error

This time, I want to discuss on an error occurred when users want to access Citrix Web Interface. This may happen for new farms or when new XML servers added to the farm. 



Issues :

• Users received below error when accessing Citrix Web Interface :
  

Troubleshooting 

1. From Citrix Web Interface server, go to application log, and search for Event ID 31003 and Event ID 30110.
2. Those Event IDs indicates that XML service transition failed.

   
   

   Event ID 31003 in Application Log

   
   

   

   Event ID 30110 in Application Log

   
   
3. Check which server(s) is/are configured as XML Service servers for the farm, and RDP to the server(s). 

Resolution :

1. go to Start > run, type regedit and press Enter.
   
   
   
   
   
2.  browse to HKLM\Software\Citrix\IMA
   
   
3. Add a new registry value (ensure it is DWORDS (32-bit) Value)
   
   
4. Set the name as UseNetworkLogon
   
   
   
   
   
   
   
5. Right-click at the newly created key, and click Modify...
   
   
   
6. Change the value data to 1. Ensure the base is Hexadecimal.
   
   
   
7. This is the final outcomes :
   
   
   
8. Go to Services, and restart Citrix Independent Management Architecture service.
   

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XTE Service Cannot be Started

Citrix XTE Server service is one of the essential service in Citrix XenApp. it is directly relates to Session Reliability. What is Session Reliability? Please read from here and here. Is Session Reliability Goood? Hmm, read this article and go figure it out. (such a lazy bum of me, huh?)

It might occurred in your environment that XTE Server service can't be started at one server, while the rest are fine. Session Reliability option is enabled from Citrix Console.  So, what's next?  

Issues :

You may received below error when you want to start XTE Server service.

 

Troubleshooting 

browse to %programfiles%\Citrix\XTE\Conf, check whether file httpd.conf is existed / is there any content inside the file.

Resolution :

1. Copy the file from server that is working fine. 
   
   

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