| I think these days we should by default think of storing blobs of data (like video files) in storage systems like S3 or the alternatives, and that ordinary filesystems should be thought of as a special case where you want to attach storage to an individual computer. Edit: I'm going to elaborate, because people are calling me naïve. Full disclosure: I work at a cloud provider on a storage team. For most people and applications, you simply don't get good value for your money by using filesystems and hard drives directly. We've tried to make things more reliable and durable with backup policies, RAID, and ZFS but the fact is all of these things come with operational and capital expenditures that compare unfavorably with common cloud storage options. There are some good technical reasons why cloud storage is better: basically technologies like RAID and ZFS are attempts to make each layer of your storage stack completely durable and available, but this approach is not competitive with the way cloud storage is typically implemented, which is to build a reliable distributed service on top of cheap hardware. Consider RAID 1, for example. This gives you N+1 redundancy at the drive level for an individual computer. This worked in the 1990s but drives are bigger and RAID failure modes suck with larger drives—it's worrying how common it is to see errors when rebuilding a degraded RAID array, and at N+1 that means that your data is lost from that computer. Essentially, with modern drive sizes (4+ TB seems pretty common these days) a RAID 1 array should always be considered N+0 instead of N+1. Cloud storage is implemented much more intelligently. If you have distributed storage, you can simply spread files across computers in different DCs and use error correction codes to increase the redundancy. You can get more nines of durability and availability for less money this way. You end up with something like 33% overhead on disk space instead of 300% overhead, and you're also off the hook for a big chunk of your capacity planning and various other operational expenditures. These days I would consider starting from "this file is in cloud storage, and we have a local cache" rather than "this file is in local storage, but we have a cloud backup". That's really all I'm saying. It also won't always be competitive. Sometimes cloud storage is more expensive than regular filesystems, depending on how you're using it. If you're a big company you can sometimes amortize the costs of doing it yourself better. That's all I mean by "default"—I'm going to put my data in cloud storage unless I have a compelling reason to store it some other way. |