There are basically two types of storage. Logs and blobs. Logs were described in the blog post, but blobs weren't. Blobs are mostly images that type of stuff, and are stored in leveldb. It can easily get to 1Gb or more. The trick is that blobs aren't sigchained, so they could be garbage collected, and that is something that we're working on. Logs can't be garbage collected, but they grow slower than blobs do, and are usually around 100 Mb or less.