I run Bitcoin on my raspberry pi 3. I have been storing the blockchain on a 128 GB USB SSD drive:
The performance has been great and I've never had any problems. However, the blockchain recently grew too large so I bought the exact same type of drive, just bigger: 512 GB. And now the computer is embarrassingly slow. Operations that take seconds when the drive was small are taking all day now.
The system itself is still running/booting from a 16GB SD card and that hasn't changed.
I've even run
hdparm tests on both USB drives-- and the bigger drive is faster!!
Both USB drives were formatted FAT/Master Boot Record on my OSX machine. I've tried copying the 128 GB of data over to the new drive, and I've also tried starting with the 512 GB drive totally empty. I've even tried using a better power supply. I'm totally stumped. What on earth could possibly be slowing down the processor?!
I also am having trouble making partitions and even formatting this drive. However, when I attach the drive my OSX machine I can format it and use it and it works FINE.