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I am planning to reinstall windows on my computer (clean install, meaning formatting the disk).

I already have 2 partitions, C: and D:, and I already have my important stuff in D: (the same physical hard drive).

My Windows 7 license is an upgrade, not a full, therefore, I will not format C: first and then install Windows, but let the installation disc do the formatting and install.

When reinstalling Windows in C: with a clean install (formatting), is there ANY risk on deleting stuff on the D: partition, or is it perfectly safe?

Note that of course I do know that there are always risks and I should have another backup elsewhere of my stuff in D, but let's assume physical damage is not an issue. Is there still any software-related issue in the formatting process that may delete D:?

The whole point is that I want to fresh install windows 7 and I don't want to wait long for a complete D: backup, so should I just do it with no worries?

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closed as not a real question by Canadian Luke, aliasgar, Simon Sheehan, Randolph West, BBlake Sep 19 '12 at 11:39

It's difficult to tell what is being asked here. This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form. For help clarifying this question so that it can be reopened, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

Your question answers itself. There are always risks. If you care about the data, you should have another backup elsewhere. You ask if you should do it with no worries, and the answer is "no". As you said, "there are always risks". – David Schwartz Sep 18 '12 at 18:01
Well, of course, but i want to know an approximate failure probability or to know if someone has ever had that specific problem. I have never heard of it, but that is precisely why i ask all of you. – DiegoDD Sep 18 '12 at 18:04
In my experience, if you care about the files, the probability is near 100%. Also, after you lose the data, you will promise yourself that from now on you will always take a backup. – David Schwartz Sep 18 '12 at 18:06

Formatting one partition is unlikely to harm another partition unless you make the mistake of choosing the wrong partition to format. However, it's always advisable to make a full backup of your important data before doing a reinstall. External drives are not all that expensive in this day and age, so there's really no excuse not to have at least that kind of backup.

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Thanks, in fact, I already do have an external drive, and I am on the process of backing up D:, but since I have a lot of old stuff there, I want to first "clean" D and then back it up, because there is no point of having a backup of obsolete files, not to say it would take more space. since there is a lot of stuff to check, it has already taken a lot of time; although i have already backed up a big chunk of important files to the external drive, the rest will take a bit more time. – DiegoDD Sep 18 '12 at 18:01

Have I used Windows installation media hundreds of times to do exactly this? Yes. Does that mean there is no possibility of a software bug or even a drive firmware bug or similar messing things up quite badly? No. So honestly, what sort of "approximate failure probability" are you looking for, that is not going to be some completely bogus made-up number?

Sounds like you're just looking for multiple confirmations from people here that it's safe to go ahead without taking a full backup first, because sorting through your files is gonna take a long time. The way I see it, you either go ahead knowing full well that there is a risk of losing your data, however small the probability of that happening might be. Or else you spend the time to do it properly, by backing up now, formatting, then sorting at leisure later.

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