On 31 January 2011 21:09, Roberto Spadim <roberto@xxxxxxxxxxxxx> wrote: > you psu must be dimensioned to work with everythink at full work load > (itÂs a real production NAS right?! not a test) > your SAS/IDE/SATA controller and HDD manual should be checked > how hdd wake up? one command (read/write) over sata/sas/ide channel wake it up? > on linux raid we have a read algorithm and a write algorithm > if a raid1 write occur all disks will wake up > if a raid1 (raid0 or another) read occur only the disk will wake up > > but check you SATA/IDE/SATA controller, how it wake up your disk, and > how you hdd wake up > > 2011/1/31 Piergiorgio Sartor <piergiorgio.sartor@xxxxxxxx>: >> Hi all, >> >> assuming there is a NAS, with, for example, 10 HDDs >> in RAID-6. Assuming the HDDs are put in standby, in >> order to save energy, when the NAS is not used. >> How is the spin up sequence when the corresponding >> /dev/mdX device is accessed? >> Will the system spin up one HDD at time or all together? >> >> Obviously, one at time will limit the peak current, >> thus allowing a better dimensioned PSU, working almost >> always around the optimal efficiency point. >> >> Thanks a lot for any information on the topic, >> >> bye, >> >> -- >> >> 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 Âhttp://vger.kernel.org/majordomo-info.html >> > > > > -- > Roberto Spadim > Spadim Technology / SPAEmpresarial > -- > To unsubscribe from this list: send the line "unsubscribe linux-raid" in > the body of a message to majordomo@xxxxxxxxxxxxxxx > More majordomo info at Âhttp://vger.kernel.org/majordomo-info.html > I would guess, that on a RAID0 setup, any read to that md device would wake every disk up in that setup. No? // Mathias -- 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
