Date: Wed, 04 Mar 1998 15:28:04 -0800 (PST) From: Simon Shapiro <shimon@simon-shapiro.org> To: Wilko Bulte <wilko@yedi.iaf.nl> Cc: julian@whistle.com, hackers@FreeBSD.ORG Subject: Re: SCSI Bus redundancy... Message-ID: <XFMail.980304152804.shimon@simon-shapiro.org> In-Reply-To: <199803042154.WAA04141@yedi.iaf.nl>
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On 04-Mar-98 Wilko Bulte wrote: ... > free, like a $10-15 pricepoint. No real use for it here, but maybe fun > to play with. Like the FDDI network here ;-) I am using FDDI (CDDI) here on my development setup. The DEC cards supported by FreeBSD. Very boring setup; You plug them in and it works. Nice thing is it provides redundancy and does not need an expensive switch. I use the Intel 100B cards for 100mbit PtP. Just as boring but twice as fast. (boring here is the ultimate compliment a kernel subsystem can have; it works well without any problems). ... > An extra power supply is money well spent. We ship all our standalone > arrays at least with N+1, optional 2N power. 2N gives you 2 seperate > power entry points to the power grid. Now we only need to educate people > to use two different power branches (phases? what's the right English > term?) The old DPT 9W tower (made by DEC) had an interesting feature, where the power INPUT was switchable too. If the AC to one supply went dowm it will draw AC from the other. Yes, 2N P/S is trivial to do (2 diods/circuit if I remember right) and cheap. Technically, you want each supply fed from a different phase. In the US they are referredto as ``independant circuits''. I have seen people paying lots of money to get that, where they have 220V right in the same room (220BAC in the US is 2-phases, 180 degrees apart, unlike the European 3 phasees 120 degrees apart. Yest, you can get 3phase circuits in the US too). The hot wire in a 220VAC, in the us is 117VAC to ground, 220VAC hot-hot. >> To have the kernel actually checkpoint itself, with any better >> resolution, >> or intelligence will have to change too many things. I am trying to >> make > > OK, that was my original question. Had a bad feeling about exactly what > you mention here. What's bad? I would like to know if you think there is a mistake here. Simon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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