For my clients with Premium hosting plans (WPengine Discounted Hosting) there is a great option to get extended storage. With LargeFS you need an Amazon S3 account, and you would send us your account details to setup your LargeFS account. Once the files are over sixty days old, the system will move them over to your Amazon S3 account. You can create a new bucket for each domain if you want. See more discounted WPEngine plans and coupons.
You can sign up for a free S3 account with 5GB of storage. Update: they now offer 10 GB but only for glacier storage. Glacier storage is not compatible with largeFS
Once LargeFS is setup our system will tell the site to retrieve the files from Amazon S3 when these are called.
They have a blog article that goes into depth about the LargeFS system.
Historically it was challenging to cleanly integrate the standard WordPress UI with the scale of S3. For example, there were often problems uploading images through the media uploader …LargeFS retains the advantages of S3 while mitigating the downsides, in many respects simply because it’s running at WP Engine. Just like the rest of our infrastructure, LargeFS is fully managed by WP Engine — all you have to do is create an S3 account and set us up with credentials to read and write in it.