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For decades, the storage market has been dominated by proprietary SAN storage. In the context of cloud, different object cloud storage methods have emerged. Object storage offers open source, scalable storage, and Ceph storage is among the most commonly used object storage options today.
Ceph storage has become increasingly popular for multiple reasons. First, it is open source. Open source means that no licensing fees are involved for using Ceph. As a result, Ceph will always be cheaper than proprietary storage options. But this doesn't really make Ceph storage unique. Other open source storage techniques have emerged without posing a real threat to traditional SAN storage.
Another reason for the emergence of Ceph storage is that it is software-defined, no longer dependent on expensive hardware. With Ceph, commodity hardware can be used to build a storage product that is just as scalable and flexible as any SAN storage system. Ceph can be installed on common server hardware, instead of top-grade specialized storage hardware, so even with a budget below $10,000, you can build a great Ceph storage system.
Ceph also has the benefit of scalability. There's no need to purchase additional licenses for working with Ceph; if you need more capacity, you just add more servers. You can manage as many nodes as you want as one consistent Ceph storage system.
One unique aspect of Ceph is that it provides multiple interfaces to access the storage. It offers an object storage interface, a block storage interface and a file storage interface. This means that, no matter how you want to connect to Ceph, it's possible. If you want to use Ceph as cloud storage, you'll connect your applications directly to the object storage interface, which is provided by the Ceph Reliable Autonomic Distributed Object Store (RADOS) Gateway. And if you'd rather integrate Ceph as a block device in the client OS, that can be done with the RADOS Block Device. The Ceph File System driver allows you to mount Ceph into the client environment.
Ceph storage offers common features found in any enterprise-grade storage product. Think of features like replication, snapshots, thin provisioning and self-healing. As a generic guideline, if it's available in other enterprise storage products, you'll find it in Ceph.
Arguments against Ceph
So, does all this mean that there are no reasons to stick with your current storage system? Well, there are some reasons not to like Ceph. The most prominent reason is that Ceph is all about software, not about infrastructure. You may very well have blazing fast storage, but your clients will need to connect to it as well. To deliver the synchronization that is required in a Ceph environment, you'll need networking -- fast networking. A gigabit is nice for test environments, but you'll need 10 Gb to cope with the large amounts of data that need to be synchronized -- if not more. So, some say that the money you'll save on storage hardware will instead be spent on network infrastructure. However, if you're using replicated SAN storage, you'll also need fast networking to deal with the replication load.
Another argument against Ceph storage is that open source doesn't necessarily mean that it is free. If you're using Ceph in an enterprise environment, you may use free and open source Ceph. But if all of your company data is stored on Ceph, you might be interested in purchasing a support entitlement as well. In this situation, Ceph wouldn't be free. When using Ceph with a support license, however, you'll pay for the support license only and not for the cost of developing the software behind it.
If you look at the feature set currently offered by Ceph storage, it's fair to say that a Ceph architecture can compete with any proprietary SAN storage. No matter how you look at Ceph pricing, it will be cheaper than proprietary SAN storage. If you look at the different interfaces that Ceph storage provides to clients to connect, it can compete with any proprietary SAN product. It is fair to conclude that, with all of its benefits and flaws, Ceph is here to stay and is a viable alternative to proprietary SAN storage.