What’s So Bad About POSIX I/O?

September 11, 2017 Glenn Lockwood

POSIX I/O is almost universally agreed to be one of the most significant limitations standing in the way of I/O performance exascale system designs push 100,000 client nodes.

The desire to kill off POSIX I/O is a commonly beaten drum among high-performance computing experts, and a variety of new approaches—ranging from I/O forwarding layers, user-space I/O stacks, and completely new I/O interfaces—are bandied about as remedies to the impending exascale I/O crisis.

However, it is much less common to hear exactly why POSIX I/O is so detrimental to scalability and performance, and what needs to change to have a suitably …