I got two drives of the same model which are connected using SATA.
When benchmarking read speeds using hdparm -t /dev/sdX, speeds of about 160MB/s are returned. When benchmarking write-speed using dd if=/dev/zero of=testfile bs=1M count=500 conv=fdatasync, speeds of about 140MB/s are returned.
However, when copying a single 10GB-file using rsync --progress /mnt/hd1/file /mnt/hd2/file, the writespeed is only about 35MB/s.
Why is it so slow? How can I make it faster?
Best Answer
According to many sites I found while researching this issue (for example this one), this is just normal as the bottleneck of rsync usually is CPU-power.
Results with dd and cp were near the speeds I initially had benchmarked. Seems like a 2,2Ghz dual core is just not enough for hdd-speed rsync.
During further research I also found out about this:
Rsync always checksums the whole file which takes alot of time. Using the patch mentioned above I managed to increase rsync speed to about 90MB/s. Still not great, but much better then before. Sadly, the patch has not made it into the rsync-trunk.