On Sun, Dec 16, 2007 at 02:57:16PM -0800, kelsey hudson wrote:
Not only this, but I mentioned IO operation reordering. The hardware controllers are *very* good about understanding that seeks are bad and to avoid them at all costs. So, it'll internally reorder all the IO operations sent to it before flushing it to disk or doing a media read.
So how does this interact with the filesystems needing certain guarantees about certain writes needing to happen before certain others. Some HW raids have battery-backed RAM so that they can finish writes when the power is restored. A niave software or HW raid could end up being less reliable than just a single disc, at least as far as handling bad powerdowns goes. RAID seems to be trying to solve several different problems. One is performance, and another is reliability. Dave -- [email protected] http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
