I just did the Windows 10 Anniversary update. It takes a long time and reboots twice. It definitely messed up my system, so I would take care to unplug all of your drives except for C:/.
In my system I have C:/Windows - SSD, D:/Data, E:/Backup, F:/DVD and G:/Games - SSD.
After the update the G:/ drive was gone, low level formatted gone. I had to create a new volume and restore from backup.
Sounds like everything went as expected. Didn't see anything weird there with that windows update.
so did mine
mine is untouched, all I had to do was the typical reconfigure nvidia surround
Since the the update, i have had to go through many minor settings and reset them to my preferred. Other than that really hasn't been that bad. Oddly no straight up broken stuff ......... shrugs :) Has been a little buggy and weird but getting my settings back to my preferred has so far cured the ills. Hurts to say this, even feels snappier.
Windows 10 Anniversary Update may affect and even delete other partitions on the same disk, OMGUbuntu is reporting, citing several complaints by users. "Broken boot loaders on an update are one thing but losing data, even entire partitions?" asks the author. Microsoft-centric news blog WindowsReport is corroborating on the report, adding that in some cases, the new OS was not able to detect some partitions. It says (edited):
Many users are reporting that some of their partitions disappeared after installing the Anniversary Update. Usually, it's the smallest partition that disappears, although we couldn't say for sure whether the partition is deleted or if Windows simply doesn't detect it. Some users are saying that the partition is not allocated, while others can detect it once they install third-party partition management applications.
We have reached out to Microsoft for clarification, and will update the post when we hear back from them.