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
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