The update will attempt to patch the recovery partition, but here lies the problem: Over the years Microsoft has changed its mind on how big the recovery partition should be and exactly where it should be located. Depending on how old your deployment images are, that is when you first installed your base of Windows 10 machines, and if you haven’t redeployed operating systems, you may find that many of your installed systems will fail to install this update.
Managing vulnerable disk partitions
If you have no recovery partition, your system is not at risk from this vulnerability, but the update will fail, nonetheless. Microsoft has stated it is working on a fix for this issue in an upcoming release. If you have a recovery partition but it doesn’t have enough free space — a minimum of 250 MB — this too will trigger the update to fail.
If your recovery partition is to the left of the C drive in your deployments, resizing the recovery partition may not be able to be accomplished without a great deal of redeployment planning. If the recovery partition is to the right of the main C drive, then you can use scripts to shrink down a bit of the main C hard drive and assign the space to the recovery partition allowing the update to succeed.
In the past, even Microsoft has made changes in their documentation to when and what disk configurations are most important. In a test of several drive configurations at my office I found a mixture of systems that had no recovery partitions. These I flagged as having the potential for outright failure but not vulnerable to the security vulnerability. Next, I found a series of devices that gave me confusing drive specifications.
Susan Bradley
In the Drive management console, I found systems that had two recovery partitions, one in front of the C drive and the other behind it. In these systems, I found that it was the partition behind the C drive that was still the one that the system had in use. I was able to determine this by going into an Advanced PowerShell window and typing in reagentc/info. This provided the identification of the partition that Windows saw as the active recovery partition.
Susan Bradley
Don’t be fooled by the report that the recovery partition is 100% free. In reality, when using a partition tool, the free space in partition is vastly under the recommended 250 MB free. In fact, many configuration specialists are now recommending a configuration that begins the deployments with at least a 1 GB recovery partition. This will give enough space for future patching of this special partition.
