Scalability remains a key concern for organizations of all sizes. Enterprise computing environments commonly face very large workloads, or very fast-growing workloads, and cannot afford to have hardware or software limit business operations. Smaller organizations have an equally urgent need for confidence that a platform will be able to keep up with their requirements as they grow. Users therefore need to ensure that their platforms offer enough headroom for the future.

With more and more of the industry's most demanding workloads being entrusted to UNIX systems, the upper limits of their scalability are becoming increasingly significant, as they have to support ever large configurations of hardware and storage. The scalability limits of an operating system are fundamentally determined by several criteria, including vertical scalability, i.e. it ability to scale 'up' on large Symmetric Multiprocessing (SMP) systems; horizontal scalability, i.e. its ability to support scaling 'out' on clusters; the scalability of its storage functions; and the quality of its tools to help administrators optimize performance.

Click on one of the links below to see how these systems compare in each of these criteria:

	Scale-Up Support (14 ratings)
	Scale-Out Support (6 ratings)
	Storage Scalability (7 ratings)
	Optimization Tools (7 ratings)