Rebranding the product as Web Object Scaler (WOS) 360, DataDirect Networks (DDN) expanded its ObjectAssure (OA) erasure coding capabilities in the WOS 2.5 core software. The new Global OA is designed mainly for archiving and uses DDN's WAN optimization to reduce network overhead.
The DDN WOS 7000 archive node is similar to the WOS 7000 appliance, but it has a single controller and CPU, while the 7000 appliance uses two controllers and CPUs. Both appliances have 60 slots for drives. The archive node supports 4 TB SAS drives and 10 Gigabit Ethernet (GbE), 20 GbE and InfiniBand connectivity. Customers can cluster up to 256 nodes, and the system supports 32 trillion objects.
With the addition of Global OA, DDN now has four data protection schemes: replication to store three copies of data, Local OA to protect data at one site, Replicated OA to protect data at two sites and Global OA to go beyond two sites.
Each one has its strengths and drawbacks. Three-copy replication provides the best performance and durability, but triples the raw storage requirement. It's often used for content delivery and collaboration use cases when fast access is required. Local OA -- an alternative to traditional RAID -- reduces the amount of storage required and is often used for frequently accessed data; however, it gives customers only one copy of the data (another copy can be stored on tape). With Replicated OA, data is copied to a second site. DDN claims its WAN optimization lowers network overhead significantly, making Replicated OA a good choice for large object environments that span data centers. However, it requires more storage than Local or Global OA.
Global OA uses the same zone scheme as DDN's other types of erasure coding. Customers create zones in a WOS cluster, assign nodes in each zone and create policies for managing objects in each cluster.
"We do erasure coding on two levels," said WOS marketing director Tom Leyden. "First, we apply erasure coding locally within a zone. When you have to rebuild, you have sufficient data inside your zone to do rebuilds, and you don't have to send data over the WAN. Our second level of erasure coding goes across zones. If a full site fails, customers can still access the data. You have to go over the network when you do writes, but rebuilds only need to get data locally."
Leyden said he expects Global OA to replace Replicated OA for many customers. Global OA lacks the performance of DDN's other data protection methods, but requires the least amount of raw storage.
"This gives DDN four flavors of data protection. Most object storage vendors have one or two options," said Ray Lucchesi, president of Broomfield, Colo.-based Silverton Consulting Inc. "WOS has a local copy of RAID for failure of a disk, replicated erasure coding for environments where you might have a whole site go down or replication across sites."
In a recent Gartner report analyzing object storage products, Critical Capabilities of Object Storage, analysts Arun Chandrasekaran and Alan Dayley gave DDN WOS high grades for capacity, performance and resiliency. However, WOS scored low for security because it lacks features such as encryption and write once, read many. The new WOS release didn't address those shortcomings.
DDN WOS 360 is expected to ship this month, with the archive node following in April. DDN said pricing will be announced when the products become generally available.