Windows 10 anniversary update alters partitions and disables Linux
 

Not only this garbage from Microsoft crashed twice while installing but also damaged my Slackware Linux install.
Thankfully my Linux install is on a separate drive and only /home is on a partition on a drive that's shared with Windows 10.
So my Slackware would boot and root log in worked fine but my user log in threw a bunch of permission errors and access denied errors when doing "startx" and X would not start.
Upon further investigation I noticed my user log in ended up with home being in /.
It appears Windows added a partition just before my home partition and that changed my home from being on /dev/sda4 to /dev/sda5.
After making an adjustment in fstab, Slackware is working again.
Windows 10 also came back from the dead after that.

I'm going to have to rethink my sharing a data partition on the same drive with Windows 10.
As my home partition contains the bulk of my data, it's definitely not safe with Windows 10 having access to the same drive.
Windows 10 update never asked or warned about making partition changes to the drive!
After restart all I got was that stupid spinning dotted circle.
Microsoft - still a criminal organization and a fail as always!

P.S. I wanted to add that my system is UEFI enabled (although the large drive is only 2Tb).
UEFI is another useless garbage that has zero practical benefit, no user interface, and only is designed to take control from the computer owner and give it to any trash app that asks for it.

Yep. They have always been and probably will always be, one of the worst "corporate citizens" in the history of the industrialized world.
They can't be trusted any farther than you could pick up the Eiffel Tower and throw it.

Windows 10 anniversary update alters partitions and disables Linux
 

The more things change, the more they stay the same...

It has always been this way. Installing any version of Windows will damage pre-existing installations of any other OS.

The golden rule is: Don't install Windows unless you have backups/images of the other OSs on the machine. Windows wants to be the sole OS on the machine. It's designed that way and always has been.

Sharing a data partition with Windows is not something I would do on a desktop machine... especially not the one containing /home.

UEFI is actually quite easy to use. I prefer using it to the old way. The best advice I can give you in this regard is to use rEFInd. I've been tinkering with some of the BSDs recently, and UEFI has made it trivially easy to boot them.

I just cannot understand why otherwise intelligent people continue to install the M$ malware-OS...

I know, "I have to because {insert reason here}". But you don't.

Let me just say that eradicating everything M$, and I mean all of it totally, from my life, home, general vicinity long ago has been the only true path to digital peace I have found. If I can do it, you can do it! ;)

Disagree 100%% with everything the OP says.

UEFI is the best thing IMO to happen to computers in a LONG time. It's so much simpler to manage, easier to work with, and more stable than MBR booting when something goes wrong. I love it, and after having used EFI booting, would never be willing to go back to MBR booting.

Also, updated 2 systems that dual boot (1 Fedora 24 + Win10 Pro, the other Debian Stretch + Win10 Pro), neither had the slightest hiccup after installing the anniversary update. Maybe your install had an issue, but didn't create new partitions on my system, didn't have issues booting on my systems, didn't cause any issues with the Linux install on my systems. Not a fan of the anniversary update, think the Start Menu is difficult to navigate now, but it didn't cause any issues.

Windows 10 anniversary update alters partitions and disables Linux
 

I have to because the mob who provide our industry-specific software only write for Windows. They have a large enough customer base that they can dictate what their software will run on.

Does Windows have things that Linux can not do ?

Yes, it has my clients that use it and the money from my clients pays for my rent and my food ;)

I do use non-Microsoft tools whenever I can, OpenMediaVault for NAS, pfSense (BSD, I know), and had used some file servers based on Slackware.
But the bulk of business software is Windows. Outlook rules the office email, MS Office the office apps, and everything from Sage and Intuit is Windows only.
That's what most small business run.
And so at home I have to have couple Windows installs for testing etc. No, virtual machines don't cut it. And yes, I have those too.

Windows 7 coexisted with Linux fine. But now with Windows 10, UEFI, Secure Boot, Microsoft started an all out war.

You can disagree.
But the fact is UEFI is an black box OS underneath your real OS, has no interface when starting the computer - if you know some magic how to work UEFI with your keyboard before your Windows or Linux boots, then please let me know.
And no, I don't mean booting from removable media - UEFI can disable that - fact is UEFI with Secure Boot can completely take control and prevent you from using your computer - yes, it is a worst case scenario and sounds far fetched but tell me it can't be done.

And the fact the Windows update had issues and screwed up everything on my computer is the core of my post and my complaint so you saying that you had no problems is rather silly, because with our 3 updates, the Windows update failure is now at about 33% ;)
But my point is, even if small percentage of updates fails, it's unacceptable and data loss is even more unacceptable. I have not lost any data this time but it was close and cost me some wasted time that's 100% Microsoft's fault.
Yes, the Start Menu is useless again - I'm installing Classic Shell for my clients.

In theory you are right.
But the reality is that not only I have to have a Windows install if I want to assist my clients.
But also the best system I have - i7 6th gen, 16GB RAM, mSata boot drive, and QHD monitor (it's a Dell XPS one gifted to me) - I want to use for video editing with Edius - Windows only video editing software I learned and love and there is no Linux equivalent, not even close.
And I wanted to make the same machine also my Slackware Linux daily driver but now I have to figure out how to neuter Windows 10 so it doesn't damage my data.
Yes, I know, backups. I have those but still, every time this happens it's a hassle, downtime, etc.
But I will have to disable Windows update completely and only run it at some intervals when I have time for emergencies and have "0second" backup.
Please don't post some nonsense about how Windows updates are essential and I will start bleeding from all my body's openings and die withing a few days because my computer will be hacked to death.

I have Windows 10 Anniversary on my PC on /dev/sda and Slackware on /dev/sdb. So far my system is using Grub installed to /dev/sdb separate from ntldr on /dev/sda and everything boots and works fine here.

Also, please refrain from saying any OS is malware loaded. That is complete bullcrap and FUD. I'm not a fan of Windows, but it's not a bad OS. It's no Slackware, but it's tolerable for it's uses.

Any OS is vulnerable to a hacker with enough skills to break in, or a unskilled user who clicks on a website full of porn.

Sorry for the OT, but I want to inject this. Saying Windows is malware ridden is a strech, spyware is a better word for it. If you don't believe me just read the so-called "Privacy Statement" for using M$ software. Make sure you expand and read the first section called "Personal Data We Collect" by clicking on "Learn More" at the bottom of the section.

https://privacy.microsoft.com/en-us/privacystatement/

They have the nads to say "Your privacy is important to us."

And there is no way to turn off "telemetry". You can minimize the amount, but you cannot turn it off, and M$ just re-enables it with every update.

Have seen anecdotes of this update taking out NTFS partitions as well. Seems more likely the result of laying off a good chunk of their QA staff rather than targeting other operating systems. Be slow to attribute to malice that which is adequately explained by stupidity.

That is the most common excuse*, but having trodden that same path all I can say is that if you want to be free of it, find new clients without that requirement, or help educate your clients to understand why they also need to move to something better.

I do not say that flippantly and I know it is problematic and specific to your own situation... but, I did it and it was worth any imagined pain I experienced in the process. In the end I was glad to see my last M$ requirement hit the door and everything that replaced them was better by far. It is really just a matter of making up your own mind to begin moving in that direction, the momentum builds itself.

*excuse, please do not think I am being insulting or argumentative, I am not... but a little sarcasm makes the point. Kind of like the smoker or alcoholic friend who is going to quit soon... you love them dearly but it does them no good to go along with the lie they tell themselves... you just have to confront it!

Well, in the case of W10, if it is installed then your computing uses are already hacked. The OS is the hack.

What I find most perplexing is how quickly most everyone seemed to resign themselves to the HUGE move of the "privacy" bar that is W10, as being just normal. It was an outrage!

If "real" malware doing exactly the same things were on your system, few would allow it for a single day! They would remove, purge, reinstall, whatever! But the wide acceptance of W10 spyware doing the same things... it is baffling.

In another post here you make a distinction of sorts between spyware and malware. You are correct that w10 is spyware, but I see little reason to differentiate between the two terms. Perhaps we should call it all exploit-ware, because all of it is about exploitation.

Privacy is not "policy", its source is mutual respect. If I respect you as an intelligent being of equal standing to myself, then I respect your desire for privacy because I have a similar desire and want you to respect mine as well. When we respect each other as equals, we co-exist in mutually beneficial equillibrium - peace.

Those who do not respect your privacy do so because they do not respect your person. There is nothing at all mutually respectful in the actions of M$ or of those who would exploit you in any other way. Their "privacy policy" is just window dressing to give the appearance of legitimacy to their exploitations.

Anyway, again, not trying to be argumentative. Just encouraging those who really want to break the addiction, it can be done.

So why is this a problem? Yes, everyone who uses Windows uses Outlook for email and MS Office for office apps. But email is client-agnostic. You can use Sylpheed or Thunderbird or Evolution and still exchange emails with clients who use Outlook. You can use LibreOffice yourself and still produce documents and spreadsheets in formats that your clients can read using MS Office. And you can import into LibreOffice any documents that they send to you. You might need a specialised Windows machine to run Sage and Intuit software but you might also be able to run them using Virtualbox or Wine.

If you really really have to have a specialised Windows machine for certain software, you could just keep it off the Internet and then you could use XP or Windows 8 rather than Windows 10.