@johnnie.black Not always Because the kernel does delayed writes to the physical device, if you have a few drives, and your allocation mode is set to "Most Free", the files all go to different drives.
When this happens, you'll see in the dashboard that the system has actually switched to rwm from reconstruct, because reads happen after a file is fully written (updating file system tables / whatnot) If you're transferring a ton of files, of varying sizes, the drives all have the same free space, and the allocation method is most free the system will stay in rwm for upwards of 90% of the time.
Drove me nuts sorting that out last night.
A bit of an edge case to report to Tom, but I did come to the firm conclusion that I absolutely hate how he's got it switching back and forth now.