Why are DD results dependant on OS?
I'm not to familiar with how DD works, all I know is it's useful for generating "empty" files and some people use it as a crude benchmark of disk I/O. I was running some tests on the Xen templates I received and noticed that the DD results for each OS is very random. Anybody care to shed some light on this for me?
Here are some examples (all are x86_64):
- CentOS 5.6 = 50MB/s (3 tests)
- Debian 5.0 = 71MB/s (3 tests)
- Debian 6.0 = 12-13 KB/s (4 tests, possible bug with template)
- Gentoo 2011.07 = 53MB/s (3 tests)
- Slackware 13.37 = 31-45MB/s (5 tests)
- Ubuntu 10.04 = 64-67MB/s (3 tests)
- Ubuntu 11.04 = 49-56MB/s (3 tests)