2 ms·

Hard drives are still first and foremost optimized for low cost per TB. Almost everything you're asking for would work against that goal, even if you could get

Hard drives are still first and foremost optimized for low cost per TB. Almost everything you're asking for would work against that goal, even if you could get economies of scale on these specialized drives. You would end up with little or no cost savings relative to QLC NAND, sequential read performance and random IO performance that would still be worse than QLC, and potentially higher latency than current hard drives. Seagate has been pursuing dual-actuator drives because density increases have been causing a decline in performance per TB, making the performance characteristics of big hard drives relatively more tape-like. It's a first small step in the direction of your proposals, but it doesn't seem to be a big hit so far. That indicates taking those ideas to their logical extremes is probably very uneconomical.

sitkack 5y ago
Thanks for your analysis, I appreciate it. I was kinda saying, "hey why don't we have LaserDisc sized hard drive platters, they would be HUGE!". Using lots of smaller disks has so many advantages after I thought about it. One being additive bandwidth, if a single disk is 0.2GB/s if I need 400GB/s I know I need at least 200 disks to hit average write rates of 0.4TB/s. Speaking of tape like behavior, it would seem that SMR would benefit a whole bunch from multiple actuators. It seems like rather than having dual actuators, as that doubles the number of simultaneous streams, it would help with lots of shared workload, but really that problem should be solved somewhere else -OR- widening the read head by some multiple. Instead of using a record player needle, use a rake. Interleave the tongues so there are like k tracks between splines. Also reduces the actuator travel distance. We should think of individual drives not as DIMMs but the individual chips themselves. They can be remixed into what ever your workload demands.

sitkack 5y ago

Thanks for your analysis, I appreciate it. I was kinda saying, "hey why don't we have LaserDisc sized hard drive platters, they would be HUGE!". Using lots of smaller disks has so many advantages after I thought about it. One being additive bandwidth, if a single disk is 0.2GB/s if I need 400GB/s I know I need at least 200 disks to hit average write rates of 0.4TB/s. Speaking of tape like behavior, it would seem that SMR would benefit a whole bunch from multiple actuators. It seems like rather than having dual actuators, as that doubles the number of simultaneous streams, it would help with lots of shared workload, but really that problem should be solved somewhere else -OR- widening the read head by some multiple. Instead of using a record player needle, use a rake. Interleave the tongues so there are like k tracks between splines. Also reduces the actuator travel distance. We should think of individual drives not as DIMMs but the individual chips themselves. They can be remixed into what ever your workload demands.