On 10/6/18 6:20 PM, Dave Chinner wrote: >> Can you give an example of a use case that would be negatively affected >> if this heuristic was switched from "sunit" to "sunit < swidth"? > Any time you only know a single alignment characteristic of the > underlying multi-disk storage. e.g. hardware RAID0/5/6 that sets > iomin = ioopt, multi-level RAID constructs where only the largest > alignment requirement is exposed, RAID1 devices exposing their chunk > size, remote replication chunk alignment (because remote rep. is > slow and so we need more concurrency to keep the pipeline full), > etc. So the tl;dr here is "given any iomin > 512, we should infer low seek latency and parallelism and adjust geometry accordingly?" -Eric
