Date: Fri, 13 Aug 1999 11:58:45 +0300 (IDT) From: Nadav Eiron <nadav@cs.Technion.AC.IL> To: Mike Meyer <mwm@phone.net> Cc: freebsd-chat@freebsd.org Subject: Re: On freezes in 3.2-Stable Message-ID: <Pine.GSO.3.95-heb-2.07.990813115021.3154A-100000@csd> In-Reply-To: <Pine.BSF.4.10.9908122141570.94664-100000@guru.phone.net>
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On Thu, 12 Aug 1999, Mike Meyer wrote: > On Fri, 13 Aug 1999, W Gerald Hicks wrote: > :->When I kept up with the numbers for these things in a former > :->life working for a disk manufacturer, I was always astounded > :->at how much current the drives pulled during their power-on > :->sequence. After startup, current begins to taper off rapidly. > > This stopped being relevant a long time ago, but... Moved to -chat then. > > DEC MIPS-based workstations worked around this problem by having > tweaked PROMs on their SCSI drives, with a SPIN-UP-ON-POWERON bit that > defaulted to off. Ultrix would send the drives the SCSI command to > spin them up - *after* everything else in the system was powered > on. This meant they could use a cheaper power supply, as no supported > configuration required it to deal with more than one drive spinning up > at a time. DEC used this scheme on _all_ their machines. This makes a lot of sense, at least to me, when you have many disks. I think most Alpha's do it to this day. VAXen used to do that too, and at least under VMS (never admin'ed anything else on a VAX), the console would spin up the boot device, and the mount commands would spin up the rest of the disks. I think many extenral RAID cases also power up disks sequentially to prevent overloading the power supply (DEC's StorageWorks do). > > Dealing with this was the *least* of the problems in trying to use DEC > SCSI drives on other platforms. But they could be made to work. They had a jumper - no big deal. BTW, many other disks (at least my IBM DDRS's at home) have such a jumper, only it defaults to on. > > <mike > > > > Nadav To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message
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