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In other words, in order to get any meaningful results out of a hard drive performance test, your script has to produce <b>more hard drive I/O than the computer has RAM. </b> If I understand this correctly, this means that (for example) if your computer has 1GB of RAM, then the script has to read/write at least 1GB before it starts to actually stress the hard drive. Otherwise, the data gets stored in your ram and never touches the hard drive, you have effectively benchmarked the read/write speed of your ram. :) Note that this can come in the form of lots of little files, totaling more than 1GB, or one giant file bigger that 1GB. In fact, it probably best if you do both. - --[[User:Evets|scarter4]] 14:42, 22 January 2009 (UTC)
As far as writes go, you can use fsync() to flush the buffers to disk -- the 'sync' command will do this. For reads, you'll need to clear or exceed cache in order for this to work. There are a couple of ways of doing this; one is to fill the available RAM so that little or none is available for buffering, another is to manipulate stuff in /proc
--[[User:Chris Tyler|Chris Tyler]] 15:16, 22 January 2009 (UTC)