Archive for the ‘Troubleshooting Fridays’ Category

XenServer 6.0 – Import/Export OVF

We had received several OVF from a vendor who exported their VM’s from VMWare and we needed to import them into our XenServer 6.0 environment. After learning that this functionality is now built into Citrix XenServer and no longer needing XenConverter we were excited. However our initial test to import failed. After re-reading the documentation and searching several forums, nothing appeared to resolve the problem – the import would start and several seconds later it would fail.

So we imported the images into our VMWare environment to ensure the OVF’s were good, and even exported them again just to make sure the OVF files themselves were not the issue.

We then tried to export a XenServer VM via OVF and it failed as well. However we could import and export VXA files without issues. Okay, so we have it narrowed down. A bit more research brought us to this Citrix Blog about TransferVM

We attempted this but it said that the package as already installed.

We then contact Citrix who said to try: Nagivating to /opt/xensource/packages/files/transfer-vm and then running the

However that didn’t work, it prompted for a UUID but it didn’t document anything about the UUID

We brought this back to our test environment and it worked fine, we uninstalled and then installed and our OVF imports work properly. The difference between the test environment and production is that production is in a pool, whereas the test is standalone.

I have tried to find documentation on which UUID it is looking for but at this point I’ve tried it with the pool, host, and sr UUIDs to no avail. I might have to resort to cycling hosts out of the pool into standalone mode and reinstalling the transfer-vm component and then rejoining the pool.


Unrecoverable error during 5.5 restore (from failed 5.6)

This weekend I decided to perform the upgrade of our 2 XenServer 5.5 servers in a farm configuration to 5.6 FP1. However I found conflicting information on how to perform the actual upgrade. The mistake I made was to put the server into maintenance mode before shutting it down. When performing the upgrade you must keep the pool master in normal mode, with all VMs migrated off of it, and then shut it down, which will place the farm into a recovery mode. While in this mode you are supposed to perform the implace upgrade in a rolling style. I miss read that step. So instead I ran the upgrade with the pool master in maintenance mode (thus it was no longer the true pool master as it nominated another server to be the master). Well it let me perform the upgrade, and everything appeared to be working fine. The server rebooted and I was greeted by the regular XSConsole. However I noticed two things:
1) XenCenter still saw the server as offline;
2) XSConsole showed that there were no network interfaces (NO NICS).

After researching the issue, I discovered it was caused by an improper upgrade, but no fear there is a build in restore option. Simply insert the upgrade CD and reboot… It will prompt with a restore option. And it was working great until about 95% where it errored out saying:
“Installer only supports having a single kernel of each type installed. Found 2 of kernel-xen”

Apparently if you have any prior backups on the server, plus the one made during the upgrade, the restore will fail. I found a Citrix Forum post which described by specific situtation and I attempted the recovery to no success. Only having mild Linux experience it took be a while to discover what I was missing from that forum post since I am a Microsoft guy. Here is the actual steps for a windows guy:
1) Reboot the server with the 5.6 upgrade CD
2) When prompted for advanced setup, press F2 (it will quickly auto select standard install if you aren’t watching)
3) It will prompt you for which advanced setup mode, type “shell” and press enter (no quotes)
4) Setup will continue and dump you to a command line
5) Type “vi /opt/xensource/installer/” and press enter (again, without the quotes)
6) You are now in the VI editor which is a pain, you can google for how to nagivate, but for the purposes of this, type “/kernel” – and press enter, repeat that until you see the line beginning with “assert len(out) == 1, “Installer only supports having a single kernel ”
7) with the cursor over that line, type dd (this should delete the entire line)
8) Then move the cursor over to “return out[0]” and press “a” to enter into the append mode, change it to read “return out[-1]” – then press “esc” and then type “ZZ” (Case sensative).

Error 0x8007007f: A problem is preventing Windows from accurately checking the license for this computer

After you install SP2 for Windows Server 2003 x64 you get the following error message when you try to login using local console or RDP:

A problem is preventing Windows from accurately checking the license for this computer: Error Code 0x8007007f

After performing some research on the internet, this appears to have been a very common problem. A simply reboot fo the server, after the initial post-SP2 install reboot, appears to have resolved all of the problems.

Read more…

Sonicwall Registration: DSL MTU PPPoE

A fellow technician had a problem last week with a Sonciwall TZ200 not registering properly. For no apparent reason, when he swapped out the old firewall with a new Sonicwall TZ200, he was unable to properly register the product with the vendor. After opening a support ticket with the vendor, the solution was to change the MTU for the WAN interface from 1500 to 1452.

There are a couple of reasons for this, and let’s review… Read more…

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Slow printing PDF to PCL Printers

Printing Slow with Adobe?

When same version and still slow …

Solution 1: Print the file using a PostScript printer driver
Solution 2: Print using Print as Image option in Advanced Print setup.
Solution 3: Change the Print Optimizations setting to “Disabled

Acrobat uses different printing routines based on the type of printer driver your system uses. When you use the PCL printer driver, the spool file sent to the printer is larger than it should be. When you print using the PostScript printer, you will not encounter this problem.

(Updated 07/06/2012: One of the main reasons for this performance issue can be due to printers with very little on board memory, selecting printers with larger on board memory can make a dramatic difference in your printing performance).

Tech Note: Port Conflict leading to RADIUS / IAS / Wireless issues

Apparently there is a chance that a security patch (MS 08-037) can lead to port conflict issues.

There was an issue at one of my clients this morning stemming from this.  The DNS Server was using a port that was needed for the IAS (RADIUS) Server.   The IAS service would not stay running.   As a result wireless clients could not authenticate.

Most of the details are here:

There is a registry key that behaves differently for XP/2000/2003 than for Vista/2008.  It’s “MaxUserPort”.  (My assumption is that’s why this is an issue – someone set it to an appropriate value for a new OS but it applied to all of them and ends up breaking some.) For 2000/2003 it defines the maximum range of ports available for dynamic use.  On the affected server this registry key was to 65535 with the implication that the entire port range from 1024-65535 was available for dynamic usage.  IAS could not get its reserved ports as they were in use by DNS.  Deleting the registry key sets dynamic port range back to the default of 49152-65535 and resolved the issue.  I restarted both services multiple times without conflicts.


On Windows Server 2003 and Windows 2000 Server, the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\MaxUserPort registry subkey is defined as the maximum port up to which ports may be allocated for wildcard binds. The value of the MaxUserPort registry entry defines the dynamic port range.

Installing x32 Print Drivers on a x64 Server

There is information on TechNet for how to do this:

 However I could not get this method to work.  So here are instructions which DO work

 Log into a 32 bit client system as a local administrator.  In this case I used XP.  Not sure how different this will be in Vista.

Remove any instances of the type of printer you are adding.  For example if you need to install HP LaserJet 4050 drivers on the server make sure you do not have any 4050 printers setup on the client.  Also open the Print Server Properties on the client and ensure the 4050 driver is not installed.

Create a mapped printer to the server you would like to install the drivers on.  You will be asked to install the drivers for the printer.  This installs them locally on the client.

Open the printer’s properties and select the sharing tab.  Then click on the additional drivers button at the bottom.

Then select the 2000/XP check box and click Ok.  You will then be prompted to select the location for the drivers.  Use the same path as you used to install them above.

This will copy the print drivers to the server.

If you need to install the same driver on more than one server you must repeat this entire process including removing the drivers from the client.  Based on documentation this should not be necessary but I was not able to update a second server without removing them.  When I tried to update the second server I received an error message “Windows could not locate suitable print drivers” when I tried to update the 2000/XP drivers from the sharing tab.