2 Apr
2012
2 Apr
'12
1:18 p.m.
On 2012-03-03 Adam Thompson wrote:
I have a ZFS RAIDZ3 filesystem under OpenSolaris (actually a Nexenta build so a GNU userland on top of OpenSolaris kernel).
"dd if=filename of=/dev/null bs=8k" gives me ~66Mbytes/sec. "cat filename | dd of=/dev/null bs=8k" gives me ~142Mbytes/sec.
Adam, you said you get optimal speed at 8M but your examples shows 8k! The above makes perfect sense as cat will use ibs>8k and dd is using 8k. I bet you'd get 142 if you did for the dd ibs=1M obs=8k, which is probably what the cat line is doing behind the scenes. Methinks your problem was a typo.