I am planning to do a complete format on my computer. My HDD (which everything is located) is encrypted with BitLocker. A few months ago I tried to manually decrypt the drive to not cause any error before format but it literally took ages to even decrypt. Since I don't care about the data, is it OK for me to format a Bitlocker encrypted drive? Will it cause any problems or errors?
How are you reinstalling windows? Are you going to be using a recovery partition or discs?– Will MApr 22, 2017 at 19:19
Modern rotational drives tend to have a throughput in the 50-100 MB/s range during purely sequential I/O. (Seeking can easily drop this to a few hundred kilobytes per second in the worst case, if you are IOPS-bound doing I/O on single sectors.) Thus a 4 TB drive will take at least 80,000 seconds (or thereabouts), which is a shade over 22 hours, to process. Is this in line with your relatively vague "ages"?– userApr 22, 2017 at 20:11
@MichaelKjörling yes it is.– MonkeApr 23, 2017 at 10:47
If you are not worried about date, simply format it. Bitlocker does not stop you from doing so. It won't cause any problems or errors.
There's nothing at all wrong with formatting a BitLocker-protected drive. Doing so removes BitLocker - in a sense, when you encrypt the disk you are "Formatting it with BitLocker" because BitLocker takes over the space where filesystem metadata usually goes and moves it elsewhere - and it will be as if you'd just formatted any other disk.
You will of course lose all data, even if you don't do a full format - and I recommend only doing a quick format because, as @MichaelKjorling pointed out, a full one takes approximately "ages" - because it will no longer be possible to decrypt the disk's old data. I'm guessing you're fine with that, though.