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App-V 5: Do you Still have to Run Process Monitor within the App-V Bubble when Troubleshooting Applications?

  • 아티클

If - by that question you want to know if you must start an instance of Process Monitor within the virtual application like you did in 4.x – no. You could run process Monitor inside the virtual bubble, but it will not yield you much more results. The reason behind this is simple: unlike previous versions of App-V, the REAL registry as well as the native file system – NTFS – is used in App-V 5.

In App-V 4.6 and earlier, if you did not launch process Monitor in the virtual application’s environment (usually through a command prompt) all you would capture related to the virtual application would be operations to file and registry resources outside the virtual environment. In Version 5, running Process Monitor as normal will capture access to the actual locations including registry, package store, as well as VFS (Virtual File System) COW (Copy-on-Write) locations. Why just that? Because that’s where things “actually” are located. What you will have to understand is that once the operations to where the application “thinks” it is located has been hooked in the file system and/or registry every subsequent operation will continue as such to include operations only to the:

  • Package Store

  • Integration junction points to the Package Store

  • Actual package Store paths

  • VFS COW (Copy-on-Write) checks and locations

You can see examples of these in the following screenshots from Process Monitor:

Procmon and File Operations:

As you can see above, the query to the initial location of where the virtual applications thinks it is browsing (C:\program Files (x86)\Java) is clearly not natively where it thinks it is. The App-V engine picks up for this (through relationships in memory) and the operations are redirected to the appropriate converged locations in both the User VFS COW and Package Store.

Procmon and Registry Operations

You will see similar operations when tracing specific activities to registry entries. First, where the application thinks it is supposed to be located followed by subsequent operations to the actual state-separated locations in the actual registry.

Why does Process Monitor not show every Single Operation to “Virtual Paths”

The answer is quite simple - because the App-V Client takes care of all of this behind the scenes which is why you will need to have access to and understand the FileSystemMetadata.xml file as it contains all of the file system mappings for both non-tokenized paths and tokenized paths. The easiest and most automatic relationships are the KNOWNFOLDERID paths which automatically resolve to App-V tokenized paths in memory. For non-tokenized paths, it is handled differently on process creation.

Altitude Adjustment of ProcMon Driver

When you look at the altitudes of the App-V file system drivers and their relationship to the driver altitude, you can see that the Procmon driver sits at a lower altitude by default.

This might make you explore the possibility of raising the altitude to see if Process Monitor will capture more information. Please be careful doing this as this could create problems and system instability. Altitudes are managed and allocated by Microsoft (https://msdn.microsoft.com/en-us/library/windows/hardware/dn641617.) When developers want to register altitude locations for their filter driver, they fill out a special request form. That is how tightly controlled they are in order to prevent instability.