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OneFS works exclusively with dedicated platform nodes, referred to as a “cluster.” A single cluster consists of multiple nodes, which are rack-mountable enterprise appliances containing: memory, CPU, networking, Ethernet or low-latency InfiniBand interconnects, disk controllers and storage media. As such, each node in the distributed cluster has compute as well as storage or capacity capabilities.
With the Gen6 architecture, a single chassis of four nodes in a 4RU (rack units) form factor is required to create a cluster, which scales up to 252 nodes in OneFS 8.2 and later. Individual node platforms need a minimum of three nodes and 3RU of rack space to form a cluster. There are several different types of nodes, all of which can be incorporated into a single cluster, where different nodes provide varying ratios of capacity to throughput or input/output operations per second (IOPS). Both the PowerScale chassis-based nodes, such as the H700 and A3000, and the all-flash F910, F900, F710, F600, F210, and F200 stand-alone nodes will happily co-exist within the same cluster.
Each node or chassis added to a cluster increases aggregate disk, cache, CPU, and network capacity. OneFS leverages each of the hardware building blocks, so that the whole becomes greater than the sum of the parts. The RAM is grouped together into a single coherent cache, allowing I/O on any part of the cluster to benefit from data cached anywhere. A file system journal ensures that writes that are safe across power failures. Spindles and CPU are combined to increase throughput, capacity, and IOPS as the cluster grows, for access to one file or for multiple files. A cluster’s storage capacity can range from tens of TBs up to 186 PB of raw capacity. The maximum capacity will continue to increase as storage media and node chassis continue to get denser.
The OneFS powered platform nodes are broken into several classes, or tiers, according to their functionality: