John Robinson put forth on 2/1/2011 7:10 AM: > That'd be an excessive amount of time to wait. A quarter of a second is more > than enough, a tenth of a second would probably be enough. It's just the motor > inrush current you're trying to avoid having simultaneously. The blowers in a typical 2U server chassis will have slightly more startup current draw than the drives, assuming 5 80mm blowers and 8 2.5" drives. Mobos don't do staggered startup of blowers. Thus, staggering the drive spin up is pointless. Add to that the fact that most server chassis ship with PSUs large enough to carry the current draw of anything/everything you can stuff into them. > So waiting another second for your array to wake up would mean you could use a > sensibly-sized PSU operating in its 80%+ efficiency range, rather than a huge > PSU operating inefficiently. A typical 2.5" 10K RPM 600GB enterprise HDD, such as the Seagate Savvio, has a startup draw of 24.1 watts combined from the 12v and 5v rails. A RAID/JBOD chassis of 24 such drives, which is sold by dozens of vendors today, will draw only 578.4 watts with all drives spinning up concurrently. Most such chassis on the market today are sold with 800w to 1800w redundant PSUs, again, making staggered spin up moot. -- Stan -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
