Storage at Exascale: Some Thoughts from Panasas CTO Garth Gibson
Exascale computing is not just about FLOPS. It will also require a new breed of external storage capable of feeding these exaflop beasts. Panasas co-founder and chief technology officer Garth Gibson has some ideas on how this can be accomplished and we asked him to expound on the topic in some detail.
HPCwire: What kind of storage performance will need to be delivered for exascale computing?
Garth Gibson: The top requirement for storage in an exascale supercomputer is the capability to store a checkpoint in approximately 15 minutes or less so as to keep the supercomputer busy with computational tasks most of the time. If you do a checkpoint in 15 minutes, your compute period can be as little as two and a half hours and you still spend only 10 percent of your time checkpointing. The size of the checkpoint data is determined by the memory sizing; something that some experts expect will be approximately 64 petabytes based on the power and capital costs involved. Based on that memory size, we estimate the storage system must be capable of writing at 70 terabytes per second to support a 15 minute checkpoint.
HPCwire: Given the slower performance slope of disk compared to compute, what types of hardware technologies and storage tiering will be required to provide such performance?
Gibson: While we have seen peak rates of throughput on the hundreds of gigabytes per second range today, we have to scale 1000x to get to the required write speed for exascale compute. The challenge with the 70 terabyte-per-second write requirement is that traditional disk drives will not get significantly faster over the coming decade so it will require almost 1000x the number of spindles to sustain this level of write capability.