frherbers

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About frherbers

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  1. The WD Ultrastar DC HC520 / HGST He12 should have a transfer rate of 243MiB/sec. This is true for the first two TBs, but than it degrades to only 50% in the center of the drive. Used the following script to run 5 cycles. For each cycle measured the transfer rate at each start of a TB. #!/bin/bash for run in 1 2 3 4 5 do for i in 11 0 1 2 3 4 5 6 7 8 9 10 11 do echo "RUN=$run SKIP=$i" b=`expr 1024 \* 10`k s=`expr $i \* 100`KB c=`expr 1024 \* 1` dd if=/dev/sdg bs=$b iflag=direct skip=$s count=$c status=none | pv -b -t -r >/dev/null /usr/sbin/smartctl -a /dev/sdg | grep ^194 # show temperature echo done done Each cycle showed the same transfer rate (there was no variation) at a specific TB start, independent of temperature. SKIP=0 10.0GiB 0:00:42 [ 242MiB/s] SKIP=1 10.0GiB 0:00:42 [ 242MiB/s] SKIP=2 10.0GiB 0:00:43 [ 235MiB/s] SKIP=3 10.0GiB 0:00:45 [ 226MiB/s] SKIP=4 10.0GiB 0:00:46 [ 220MiB/s] SKIP=5 10.0GiB 0:00:48 [ 210MiB/s] SKIP=6 10.0GiB 0:00:50 [ 202MiB/s] SKIP=7 10.0GiB 0:00:53 [ 192MiB/s] SKIP=8 10.0GiB 0:00:57 [ 178MiB/s] SKIP=9 10.0GiB 0:01:01 [ 166MiB/s] SKIP=10 10.0GiB 0:01:08 [ 149MiB/s] SKIP=11 10.0GiB 0:01:18 [ 129MiB/s] RUN=1 33Celsius RUN=2 39Celsius RUN=3 42Celsius RUN=4 43Celsius RUN=5 44Celsius Did somebody else notice this 50% drop of transfer rate for these drives? Did you receive a sustainable transfer rate through the drive? Hope to have some users running my script and showing their results for similar drives.