On Mon, Jul 11, 2011 at 10:23:33AM -0700, Matthew Dillon wrote: > > :The results were taken for one run only, they were not averaged. > :Howewer, I repeated many times the tests for the RAID10 and RAID0 cases, and > :the numbers were always consistent (7% variation at worst). > : > :No fancy disk scheduler was used. Besides newfs, defaults were used for > :all commands. > > Also, what blogbench command were you running?
The default: "blogbench -d /mnt/blogbench" > To get real results with > blogbench you have to remember that blogbench creates an ever-growing > data set and if the run isn't long enough the data set may not blow out > the buffer cache in one test, and blow it out in another, producing > radically different results. There was some variation but not that much; Sascha suggested I also test FreeBSD on the same hardware and it was a damn good idea. The FreeBSD write performance curve follows pretty well the theoretical performance increase of the different RAID sets. > I usually set --iterations=100 to force the blogbench data set to be > large enough to actually blow out the buffer cache. Ok. If I get enough time, I'll do a third run with this parameter. > You should include the raw blogbench output as well. It's a wall of text > but it is important because read activity can be very deceptive if a > filesystem bogs down on writes (because only writes expand the size of > the data set being read). This makes the final numbers a bit problematic, > requiring additional analysis to really understand what is going on. I'll keep the numbers in the future. -- Francois Tigeot
