Nearly 10% Loss of Capacity on Reformatting a Drive to be used in Windows?

Is it just me, or has this increased? I recently purchased one of those HGST Helium filled hard drives for storage and after formatting it went from 10TB to 9.09TB. I backed up a bunch of data to it and it red lined with nearly 1TB of head room to spare. Now I know you always lose a little capacity when you format a drive for Windows but I don't recall it being so much. Plus 'red lining' with 872 GB of space left on the drive seems a little over the top IMO. Am I missing something here, or am I just going senile.

It's the usual Windows thing. 1TB is 2^40, rather than 10^12. 10TB decimal would be reported as 9.09TB.

You haven't lost any capacity.

Drive vendors only market the storage capacity using decimal bytes. It's written on the retail package's fine print, and owner's guide.

[Seagate] Storage capacity measurement standards

Okay, that explains it. I was just panicking. It's just that at the 10TB level it seems a little excessive. Still, with 872 GB to spare getting a red line warning strikes me as being a bit premature.

Scannerman said:

Okay, that explains it. I was just panicking. It's just that at the 10TB level it seems a little excessive. Still, with 872 GB to spare getting a red line warning strikes me as being a bit premature.

Click to expand...

@Scannerman if you convert your total drive capacity of 9.09 TB TO GB it should be 9090 GB, furthermore a drive red line warning appears when you have less than 15% of that capacity and 15% of 9090 GB would mean you need at least 1363.5 GB free space to avoid the red line warning thus you only have 872 GB free space which is why you see the red line warning.

IownAmoneyPit said:

@Scannerman if you convert your total drive capacity of 9.09 TB TO GB it should be 9090 GB, furthermore a drive red line warning appears when you have less than 15% of that capacity and 15% of 9090 GB would mean you need at least 1363.5 GB free space to avoid the red line warning thus you only have 872 GB free space which is why you see the red line warning.

Click to expand...

Yeah, it makes sense to me now. Thank you. Silliest thing is that I already knew this, but I just didn't bother to sit down and make the calculations. This is my first year for buying hard drives 10TB in size and larger and it didn't seem quite right. Normally I hate huge drives and would rather have an array of drives adding up to 10TB than a single drive that size because if the drive fails that's a huge capacity and expense to replace. With a good array you just pop in another smaller, less expensive drive and let it rewrite itself back to normal. Unfortunately, there are case scenarios where one actually needs a considerable amount of capacity on a single hard drive and I just ran into that scenario this year. I also have a 12TB EXOS drive now (which of course had a good size Windows reduction) and one more HGST 10TB coming in. At some point I'm hoping to RAID the two HGST drives, but not yet as I have a ton of data to clean up first.

I haven't even done my Win 7 side yet and already the drives are filling up fast. Once I'm done with all the sifting, sorting, and organizing there shouldn't be any red bars left, but I wonder how many spare drives I'm going to be able to pull out of this crate by the time I'm done.