I was using robocopy to write to a freshly formatted 5TB Passport that's only a month old. It was about 3.8 TB of data, mostly large files (about 300 MB to 1 GB each), but towards around the 3.5TB mark, it started writing very slow. It started around 60 MB/s, then got down to around 30 MB/s (typical HDD stuff), but then it just sputters between 3 MB/s then goes back up to 30 MB/s for a second or two, then goes back to 3 MB/s.
Give it a few more minutes and now it just won't go past 5-10 MB/s.
After I was done using robocopy, I have 700 GB free and I tried to copy some 2-4 GB files using Explorer and it starts out at 30 MB/s for the first few seconds, then drops to about 6-10 MB/s. The drive utilization is at 100% and the average response times gets up to the 1200-1800ms range according to Task Manager.
Is this normal for this drive? According to WD Drive Utilities, SMART status passed, Quick Drive Test passed, Working on a Complete Drive Test now. Will take a long time according to the utility. I'm already about an hour in and it's at 30% complete. Chkdsk shows nothing wrong either.
This happened when it was brand new too but I shrugged it off because I just needed the data on there temporarily. Yesterday I needed to clear out the drive and recopy the data since everything changed and figured I'd give it a fresh start by formatting (exFAT if it makes a difference). Same behavior as before. I recalled I verified the data just fine. I don't recall if reads were slow though either.
Waiting for the Complete Drive Test to finish on the WD Drive Utilities... Is this an SMR drive? If so, is this expected behavior? Should I be worried?