On Mon, Mar 18, 2013 at 12:30:50AM +0100, Rainer Fügenstein wrote: > hi, > > for some reasons I need to keep power consumption at startup as low as > possible. since the server is booting from SSD, it is possible to send > a "start unit" (or similar) command to all SATA drives early in the > init process. > > as far as I've searchengined, the drives and the SATA controller need > to support this feature. but my assumption is that when the drives are > not needed at startup (since they would be started by the OS), the > controller won't need to support "start unit". what is your > experience on this matter? > > drives in question are WD Green 3TB drives (WDC WD30EZRX-00DC0B0), the > controllers at hand are a promise SATA 300 TX4 (don't laugh ;-) ) and > a supermicro AOC-SAT2-MV8. Hi Rainer, I'm facing a similar issue. That's what I got so far... Many HDDs, but it seems not all, support the so called Staggered Spin Up, this means they are in sleep mode, when powered up. A SATA bus scan will wake them up. The Linux AHCI driver performs, per default, but it could be changed by parameter, a serial bus scan. This means it will wake up the HDDs one after the other sequentially and not alltogether. At least, this is what I understood, but I did not tested it personally, I just trust the information I found around. Check "Linux AHCI SSS" with some search engine and some patience. Other drivers I do not know. If you boot from SSD and you program the HDDs to stay sleepy (jumper, firmware or cable select, more info at https://en.wikipedia.org/wiki/Spin-up and referenced links) it *should* work. Hope this helps, bye, pg > > tnx. > > -- > 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 -- piergiorgio -- 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
