From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Spadim Subject: Re: RAID HDDs spin up sequence Date: Mon, 31 Jan 2011 19:10:17 -0200 Message-ID: References: <20110131201823.GA15704@lazy.lzy> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: Sender: linux-raid-owner@vger.kernel.org To: Piergiorgio Sartor Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids normaly... raid1 send many writes and one read raid0 send one write and one read 2011/1/31 Roberto Spadim : > you psu must be dimensioned to work with everythink at full work load > (it=B4s 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 w= ake 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 : >> 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@vger.kernel.org >> More majordomo info at =A0http://vger.kernel.org/majordomo-info.html >> > > > > -- > Roberto Spadim > Spadim Technology / SPAEmpresarial > --=20 Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html