Yes, storing files is fast. We ran similar tests to yours and storing never was the problem, deletion also wasn't a problem as long as the number of files was i

Yes, storing files is fast. We ran similar tests to yours and storing never was the problem, deletion also wasn't a problem as long as the number of files was in the low millions. The problem comes around when you start to delete files once you have 10's of millions of entries. I helped a customer set up a CDN and this was one of the most painful mistakes I ever made to correct for. It took weeks to migrate all the data to EXT3 filesystems while the system was live. The whole point was to end up with something scaleable, the 'sweep' ran 3 months behind the write so after 90 days, with the filesystems nicely filled to 80% capacity or so we found out that deleting a single file would take an impossibly long time. In the end we found a manageable workaround, to try to select candidates for deletion on a directory-by-directory basis which improved performance to the point that we could migrate the data but it still was a pretty scary operation.