Date: Wed, 11 Apr 2007 18:23:34 -0700 From: Gary Kline <kline@tao.thought.org> To: Chuck Swiger <cswiger@mac.com> Cc: Gary Kline <kline@tao.thought.org>, freebsd-questions List <freebsd-questions@freebsd.org> Subject: Re: Automatic means for spinning down disks available? Message-ID: <20070412012334.GA45380@thought.org> In-Reply-To: <12679B53-511F-4B40-8C53-6054897F5F6B@mac.com> References: <46192C1B.4060706@u.washington.edu> <200704091751.27697.pieter@degoeje.nl> <539c60b90704111316w38017613sd50718d901d37831@mail.gmail.com> <20070411223218.GA44292@thought.org> <12679B53-511F-4B40-8C53-6054897F5F6B@mac.com>
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On Wed, Apr 11, 2007 at 04:14:33PM -0700, Chuck Swiger wrote: > On Apr 11, 2007, at 3:32 PM, Gary Kline wrote: > > Some things to consider (besides powering -down or -off drives) > > are battery backup system. Don't most UPS systems isolate your > > servers from the wall-socket? > > The better grade of UPSes do exactly that-- they provide "galvanic > isolation" by using an isolation transformer which has the primary > and secondary windings completely separated, and ensuring in the > design that you don't connect the service neutral line to the output > or load's neutral line. The load can thus either be floating or tied > to the local building ground. This type of design is known as > "double-conversion" because they always feed the input AC line > through the rectifier & DC inverter, using more power but providing > better PFC and can provide the load with an AC frequency which is > different than the input AC frequency (ie, they can provide 60Hz > output from 50Hz input, or vice versa). Years ago I spent a lot of money for a top notch surge protector. It still protects everything to this day; and very well. Now and then I'll find my LAN down, DNS too, obviously, because of a surge of one sort or another. The power here (Seattle) is pretty good -- well, except for wind storms {koff}. But I'm way past due for having the sort of higher quality UPS that you're taking about. It would be wired to a pipe struck in the earth. Floating_ground just doesn't cut it. Any models you'd recommend? How much system installation is required? I'm CAT-5A cabled. Software, no problem; anything else is. > > Cheaper UPSes, which include almost all consumer-grade models from > APC, Tripplite, etc run in "line interactive mode", which involves a > self-tapping or ferro-resonant transformer, can adjust the voltage up > or down within limits, but they do not perform PFC and cannot provide > frequency conversion, and they pass the neutral line from AC line to > load without isolation, thus passing common-mode noise through. This > design is lighter and requires fewer components (an isolation > transformer is heavier), and does not keep the DC section and > inverter always under full load, so are somewhat more efficient, but > cannot deal with frequency drift or significant voltage changes. Understand, thanks, Chuck. Here (where rubber-meets-pavement is where *not* to cheap out). > > > At what level do hard drives have identical circuitry so that > >they can be software lower-voltaged? > > The boards within a drive family might be identical (WD200BB/WD400BB/ > WD800BB/etc), but they don't deal with under-voltages at all well-- {{ this is what i was afraid of.... }} > you'll either pull excessive current through the servo and spindle > motor windings, or perhaps the drive will fail to spin up entirely. > The spindle motors are designed to spin at the calibrated speed and So, pragmatically, a drive is either going full-throttle or it's OFF. ...Hm. > won't spin at slower speeds. Somewhere, prhaps at the Gnome shutdown GUI (dialogue?) it reads: Off, Changed-user, Idle, Power-Off, Reboot, or whatever. Flame from Gnome/KDE folks to /dev/null, please. I'm guessing the "Idle" is for the laptops. YEs/no? Something else to consider here is how much power do the newer 40-60, 200-300GB drives suck up? I don't think the drain is much compared to, say, 3 CRT television sets drowning on several hours/day. Still, let's SWAG that there are 25-30 million of us nerd/geek types running at least one computer. That adds up. > > > *Except for consumer __cost__*, why don't all boxes have builtin > > batteries like laptop? ...There are lots of things to consider. > > Cost is the primary reason why boxes don't have built-in batteries. > People flinch away from paying for real RAID systems which include > battery-backup for the drives... Well, then I'm definitively part of the problem; suspect that most of my kinsfolk are too. aNy idea how mmuch of this could be solved by software? Maybe when a machine turns itself off at 03:30, it write a state-file. When it reboots {either by magic timer or by actually crawling around down there and toggling switches }, presto, you have everything just the way you left it. puts("Feedback, world?"); gary > > -- > -Chuck > -- Gary Kline kline@thought.org www.thought.org Public Service Unix
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