Microsoft is upgrading Office 365 customers to unlimited OneDrive storage, but that doesn't mean you can just put all of your files in the cloud.

OneDrive capacity has grown by leaps and bounds this year. Microsoft increased capacity 40-fold earlier this year when it bumped the humble 25 GB of storage for OneDrive for Business accounts up to 1 TB, then a mere four months later it increased it again -- this time infinitely to unlimited storage. Oddly, though, unlimited OneDrive storage doesn't translate to being able to store an unlimited amount of data in Microsoft's cloud.

I've used Box for storing my files in the cloud for years, but I decided to give OneDrive for Business a shot -- mostly because of the tight integration between Windows 8.1 (and the Windows 10 Technical Preview) and OneDrive. It seemed like it would be simpler, or more intuitive in some way -- at least in theory -- to go with the flow and use OneDrive, and since Microsoft was kind enough to boost the capacity, I figured, why not?

I cut and pasted all of the folders from my Box Sync folder over to the OneDrive for Business syncing folder, and then sat back and let the syncing begin. My OneDrive for Business account hasn't yet been pushed to unlimited, but I was only trying to sync about 75 GB or 80 GB of data, so 1 TB was plenty.

I have a broadband connection with nearly 15 Mbps upload speed, which is pretty fast, but even at that speed, it took a few days to sync 80 GB of data. Every morning, I checked the status and how many files were left to sync, and it was cruising right along. Then, one day, it reached a point where I could see the light at the end of the tunnel -- there were only 2,003 files left. However, the next morning, there were still 2,003 files left to sync. The same thing the next morning.

As far as I could tell from looking at the information on the OneDrive for Business icon in the systray, the syncing was still chugging along just fine. There were no errors -- or at least no errors relevant to the issue at hand. No matter how long it continued syncing, though, those 2,003 files stubbornly remained. Then, as I created new content and saved files to the local drive, that number would tick up -- 2,004, 2,005, 2,006. It was clear that OneDrive for Business was just not syncing any more.

Then it dawned on me. When I wrote about the increase from 25 GB to 1 TB earlier this year, a reader had emailed me to ask whether or not Microsoft was also addressing other issues -- like the maximum size allowed for a single file or the limit on the total number of files. As it turns out, Microsoft did eventually address the file size limitation -- raising the 2 GB maximum up to 10 GB. However, Microsoft has not yet done anything about the fact that it maxes out at 20,000 files -- and that is why it won't sync my remaining 2,003 files.

I contacted Microsoft support and confirmed that this is, in fact, still a limitation for OneDrive. It's a limitation that Microsoft is aware of, and one that Microsoft is working to address in the near future. But, for the time being, your OneDrive account can only handle 20,000 individual files.

You might have unlimited storage capacity with OneDrive, but the 20,000 file limitation is actually much more limiting than the total capacity. It's true that if you happen to have a library of 20,000 HD movies that are each 5 GB or more, you could use over 100 TB of storage from Microsoft -- but as I mentioned earlier, I was only uploading about 80 GB of data, and I exceeded the 20,000 file maximum. Assuming I maintained roughly the same average file size, it would take me over 300,000 files just to use up the 1 TB of storage, never mind unlimited.

In the end, I cut and pasted all of my files and folders back to the Box Sync folder. I only have 600 GB of storage available there, but it will be years before I will fill that up, and Box is capable of holding all 22,003+ of my files.

When Microsoft finally fixes the 20,000 file limitation, I might give OneDrive another chance. Will you?