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I just tested your command, and it's also very slow on my system, even with a larger block size.
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Carpetsmoker, this is something that had me puzzled from day1 while during straight dd's with no spare time to investigate. Now I see for a fact that a big buffer sometimes can cause a slow down *AND* in my case sometimes my backup's did not work. I than blame ME until I finally got a clue. Maybe it was me but that's why I always used bs=1M. It's usually faster and it have never fail. Now I know it for a fact and don't have to blame myself anymore. Check results below.
Spilt is fun to use and may even be equal to or faster than straight dd. I notice the longer it runs the CPU usages grows slowly than drop way back down again for gzip on my machine. But for LINUX with TOP OPENED it hit 100% with-in seconds and it crashed again.
FreeBSD 8.1
bs=16:
dd - 2.20% adv - 2.55% max
gzip - 76% adv - 88% max
split - 0
bs=1:
dd - 0.22% adv - 1.67% max
gzip - 62% adv - 96% max
split - 0
Code:
ARCH-2009 --- 1,504,432,145,920 bytes - 150GB = 1851sec = 30min - 1/2 hour - 81 MB/s
FBSD-bs=1M -- 1,504,432,145,920 bytes - 150GB = 2302sec = 38min - 1/2 hour - 62 MB/s
FBSD-bs=16M - 1,504,432,145,920 bytes - 150GB = 3002sec = 50min - 1---hour - 47 MB/s
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... there is a subtle difference.. on Linux people use "block" (..buffered) device nodes to access drives, but BSD's generally use "raw/character" (..unbuffered) devices instead.
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BSDfan666, what a lesson. I never had a clue. Who would have thunk it.
I did a lot of googling and now have a much better understanding of BLOCK and RAW devices. I found and lost a thread that some believe BLOCK device is still in FreeBSD and used only by the system, (That the kind of stuff I alway find) but was removed from /DEV. Kind of make since. It could break the OS if they strip it all out. It took over 30 year to write that multi-million lines of code, even before it changed hands. It takes a life time to circle Pluto twice.