My 16TB ultrastars get upwards of 180MB/s sustained read and write, these will presumably be faster than that as the density is higher.
I’m guessing that only works if the file is smaller than the RAM cache of the drives. Transfer a file that’s bigger than that, and it will go fast at first, but then fill the cache and the rate starts to drop closer to 100 MB/s.
My data hoarder drives are a pair of WD ultrastar 18TB SAS drives on RAID1, and that’s how they tend to behave.
This is for very long sustained writes, like 40TiB at a time. I can’t say I’ve ever noticed any slowdown, but I’ll keep a closer eye on it next time I do another huge copy. I’ve also never seen any kind of noticeable slowdown on my 4 8TB SATA WD golds, although they only get to about 150MB/s each.
EDIT: The effect would be obvious pretty fast at even moderate write speeds, I’ve never seen a drive with more than a GB of cache. My 16TB drives have 256MB, and the 8TB drives only 64MB of cache.
