On Friday, 19 August 2016 4:57:15 PM AEST Piers Rowan via luv-main wrote:
> > That's a tick over 8Gb/hour, what are you complaining about? :^)
> > 
> > Is that mainly due to the USB2 interface on the PI?  And what file
> > system are you running on the USB drive?

$ echo 8000/3600|bc -l
2.22222222222222222222

8Gig an hour is 2.2MB/s.  USB2 typically gives about 32MB/s nowadays, 
strangely in the days when a P3 was a new system it gave about 35MB/s.

The USB bus wouldn't be the bottleneck here.

> Its an encrypted ext3 drive, which I am sure only adds to the overhead

I just did a quick Bonni++ run on my Thinkpad T420 with a i5-2520M and a 500G 
SSD that's encrypted.  It was giving 417MB/s sequential output and 550MB/s 
sequential output with 19% CPU use.  If the SSD was capable of it then my 
Thinkpad should have been capable of around 2500MB/s encryption speed!

The i5-2520M CPU is a lot faster than what's in a RaspberryPi, but is it 1000* 
faster?  It might be worth doing a Bonnie++ run.  Also try running zcav (part 
of the Bonnie++ suite) to test sequential IO speed without encryption.

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