I have a usb3 docking station which is showing some behavior I don't understand:
#hdparm -t /dev/sdc /dev/sdc: Timing buffered disk reads: 266 MB in 3.00 seconds = 88.59 MB/sec Timing buffered disk reads: 268 MB in 3.01 seconds = 89.05 MB/sec Timing buffered disk reads: 266 MB in 3.01 seconds = 88.43 MB/sec Timing buffered disk reads: 266 MB in 3.02 seconds = 88.10 MB/sec Timing buffered disk reads: 306 MB in 3.01 seconds = 101.72 MB/sec Timing buffered disk reads: 266 MB in 3.00 seconds = 88.59 MB/sec Timing buffered disk reads: 306 MB in 3.00 seconds = 101.84 MB/sec Timing buffered disk reads: 306 MB in 3.00 seconds = 101.86 MB/sec That's all the same disk, repeating hdparm as fast as I could. The disk was not even mounted at the time, and no other disks were active. Two very different but reproducible numbers, changing values at random times. The only thing I can think of is that the disk may be doing a SMART self-test, but for some reason the USB connection prevents me from accessing the data so I can't test my theory. Any other ideas?
