[Question] - $hf_mig$ folders - remove them?
Posted 15 February 2006 - 12:34 PM
Title Edited - Please follow the forum rules from now on
-- Martin L
Posted 09 June 2009 - 03:46 AM
Posted 06 August 2009 - 10:14 AM
1. You apply a security update that installs a GDR version of File.dll with a version number of 5.2.3790.1000 and copies a hotfix version of File.dll with a version number of 5.2.3790.1000 to the %windir%\$hf_mig$ folder.
2. You apply a hotfix that includes a hotfix version of File.dll with a version number of 5.2.3790.0000.
In this scenario the hotfix installation in step 2 installs the hotfix version of File.dll (version number 5.2.3790.1000) from the %windir%\$hf_mig$ folder instead of the hotfix version of File.dll (version number 5.2.3790.0000) from the hotfix package.
...but can't find an authoritative source...
This post has been edited by hoak: 06 August 2009 - 10:22 AM
Posted 06 August 2009 - 10:25 AM
It's not documented publicly, but indeed the $hf_mig$ folder is used for uninstall of updates, and there *may* be an update out there that uses the folder to determine which binary to install, but that is not what the folder is for, and I've never personally come across one that uses the folder for anything more than uninstallation file backup. With the advent of using update.exe for XP+ updates or the servicing engine .msu's for Vista+, this should not really even be possible anymore as the update itself contains it's branching and versioning information, so unless you're running NT4 or 2000 this should be 100% safe to delete. Also, any time you install a service pack and you choose to clean up the uninstall files (Vista/Win7) or chose to install it with the switch to not save backup files (XP/2003/previous), you can safely remove the $hf_mig$ folder after installing the service pack successfully, as you can never use those files for hotfix uninstall of anything prior to the SP anyway.
If you're paranoid you can always move it's contents to another location, but the only thing I would suggest is to make sure you never delete that folder itself, only it's contents. You should be very safe in doing so.
Posted 06 August 2009 - 05:16 PM
Posted 06 August 2009 - 10:53 PM
It's more of a "just in case" rather than anything else, nothing more. Again, I've never personally seen any issues with it, but it's a "just in case" so that you don't run the risk of problems later. You're free to do what you want with your system, but I'd recommend leaving it as there's no harm in doing so, and there's at least that .001% chance of problems if you do remove it.
Posted 07 August 2009 - 06:01 AM
The absence of the folder might not block a service pack being installed, but it would mean that you run the risk of regressing some dual mode hotfixes (i.e. applicable for your current SP level and the one you are service packing up to).
We also had a few cases recently where a customer had deleted that folder and it was preventing a COM+ hotfix installation on W2K3 due to a previous QFE version from another hotfix package being missing from $hg_mig$.
All in all a low risk, but so is the disk space gained by deleting it