With a large block size, one disk remains idle while the other is reading or writing. With a small block size, dd wastes time making lost of tiny reads and writes.
The conclusion from this benchmark is that the choice of block size for dd matters (but not that much), and cat automatically finds the best way to make a fast copy: dd can only slow you down. I ran benchmarks a while ago, copying a large file rather than a partition, between two disks (on the same disk, relative timings are different): dd bs=64M 51.3 To copy a partition wholesale, use cat instead of dd. With that in mind, this is what I got (I only tested Write speed to the Device, read is typically higher): Connected Device - Connection Type - Speed (Write Speed) This tests can change depending on Device used, connection type, motherboard, type of connecting cable, filesystem type and more. Doing real tests revealed they are between 40% to 80% of that raw speed. This were my results, but first we need to know that the theoretical speeds for many transfer rates (Raw speeds) are just that, theory.
#Fastcopy tuning pro#
I was using the Asus Z87 Pro and the Intel DZ68DP. I did a couple of tests with the connection types you were using and others I had available. With pv or a very optimized bs parameter, you can do a 4 TB drive in less than 7 Hours (6 Hours 50 Minutes at a current speed of 150 MB/s). In regards to HFS+ I would not know, am just trying to help on the "speed" part.
The nice thing about pv apart from the speed is that it shows the progress, current speed, time since it began and ETA. This has to be done of course from root: pv /dev/sdb There is also pv (Needs to be installed first) that checks for the fastest speed on both drives and then proceeds on cloning. Adjusting the bs parameter can increase the speed, for example, I have 2 HDD that I know have a read/write speed greater than 100 MB/s so I do this: dd if=/dev/sda of=/dev/sdb bs=100M In my experience, I don't think there is something faster in the command line as dd. When I made my first clone, I did all of the partitions except HFS+ and it went very quickly. I have tried Clonezilla (and it was MUCH faster), but it does not support HFS+ smart copying, which I need. I need to clone the following partitions (including UUIDs) Is there a way to run this drive copy that takes less that 96 hours? I am open to using tools other than dd.
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