What's incorrect about my statement on NVME's. In any case if an app is using direct i/o then it can use as many or as few threads the CPU is capable of plus of course the amount of simultaneous accesses the I/O device can handle. If backing up / cloning from NVME1 to NVME2 takes around 1 min or so - there's either minimal data to backup or you have a super fast type of server farm computer with incredibly fast SAS etc type of connections.
Looking at the device specs of maximum data transfer rates (and it's usually not possible to drive that data rate continuously - you should be able to estimate the actual number of bytes read and written in 1 min -- and it's not that large on typical NVME devices. The problem also with a single device isn't the device per se -- it's the number of paths the I/O subsystem has to the device and whether the device allows both simulataneous / concurrent read and write accesses. With two devices one can be reading while the other writing regardless of the need for concurrent read / write databases.
I'd hate to be in an airline queue buying tickets if the DB didn't have concurrent read / write accesses!!. (Obviously there will be some record level locking - but the principle is read / write concurrent access.
As for spinners / HDD's --large capacity HDD's make for very useful large scale backup / archive of data -- e.g say you have over 6,000 - 9,000 CD's all flac ripped -- I doubt if I could even find many of those old CD's again -- long since "out of release". Playing those doesn't need huge mega fast devices. A 14TB 7200 RPM HDD is stillfor domestic users per byte the cheapest way of archiving / backing up this type and sheer volume of data -- although I agree that's a question for another thread.
@MisterEd
You can probably speed up Wifi xfer if you can ensure xfer is working at FULL duplex rather than HALF duplex if your adapter has that option available.
Cheers
jimbo
