at least on the limited number of HP drives I've worked on, it's always a different hub pully for 50hz vs. 60hz. Jay ----- Original Message ----- From: "Paul Koning" <pkoning(a)equallogic.com> To: <cctalk(a)classiccmp.org> Sent: Tuesday, February 17, 2004 3:12 PM Subject: Re: 50Hz vs 60Hz fixed drive speed ? --- [This E-mail scanned for viruses by Declude Virus]

fixed, 14" platters 7900/7905/7906 ----- Original Message ----- From: "Tom Uban" <uban(a)ubanproductions.com> To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk(a)classiccmp.org> Sent: Tuesday, February 17, 2004 3:30 PM Subject: Re: 50Hz vs 60Hz fixed drive speed ? --- [This E-mail scanned for viruses by Declude Virus]

Tom> Well if you are talking about modern hard drives, then you are Tom> of course correct. But then that wouldn't be on topic for this Tom> list. My question revolves around the old vintage hard drives Tom> with fixed platters driven by A/C motors. One data point: at least some of the DEC head-per-track fixed disks -- RS64/RC11 and RF11 -- were constructed with spindles just like modern hard drives, the motor and platter bearing assembly all a single unit. In other words, there aren't any pulleys or the like in that setup. But the motors were AC motors, so in that case you'd definitely end up with a rotation speed dependent on the power line frequency. I don't know if the 16% difference was big enough to require tweaks to the drive electronics -- the PLL in the data recovery circuit, specifically. Perhaps so. paul

On Thu, 19 Feb 2004, Tony Duell wrote: And the Quantum 8" fixed drives which used an AC motor and required different motor pulleys for 50 and 60 cps power. - don

Hi Sellam, I have no idea. Does it happen all of the time, or is it an anomaly? No one else has mentioned having a problem, but then maybe it is because they cannot reach me... --tom At 02:03 PM 2/17/2004 -0800, you wrote:

I wondered why I didn't hear from you. What IP address would you be sending from. I checked siconic.com to see if it was in my denial list, and it is not. Also, I am receiving your email to the classic list without difficulty, so unless you send it from a different IP address, I don't understand why one would be rejected and the other not. --tom At 06:05 PM 2/17/2004 -0800, you wrote:

Sellam wrote.... As of late I have noticed that more and more major mail servers will not process mail from any server who's forward and reverse dns do not match exactly. That's not a big deal, but the way some (AOL) are doing it, does violate RFC's. Specifically, even if the forward and reverses DO match, but the reverse lookup provides aliases as well, they will toss it. However, this breaks an RFC-specified way of handling delegation of subnets on uneven boundaries. *sigh* Jay West --- [This E-mail scanned for viruses by Declude Virus]

And good for them, I say. Too many places have been sloppy about rDNS for too long. Provides aliases in the sense of returning multiple PTRs, or in the sense of passing through a CNAME? I mention this because you say which sounds like RFC2317 delegation, ie, CNAMEs. But my rDNS is done 2317-style, and I've had no trouble sending to AOL (though admittedly I don't do it much). I note that your list message was emitted from 209.83.143.147. Chasing the DNS by hand, with a human's tolerance for mistakes, I find that this has the name ssh.kwcorp.com. My nameserver, though, returns SERVFAIL when queried for PTR records for it. I conjecture that this is because when the savvis.net servers (who own 143.83.209.in-addr.arpa) are queried for 147.143.83.209.in-addr.arpa, they return NS records naming dns1.anet-stl.com, but this is, strictly, a lame delegation; dns1 and dns2 .anet-stl.com do not in fact serve 147.143.83.209.in-addr.arpa - they return non-authoritative answers showing yet other nameservers. That is, I suspect the problem arises because of the attempt to delegate the same zone cut (the one at 143.83.209.in-addr.arpa) twice, rather than because of aliases - I find neither multiple-PTR nor CNAME involvement here. /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

There certainly is no such de-facto requirement, whatever there may be de-jure. Just now, for example, I did traceroutes to 218.16.120.204 and 221.4.203.28, two Chinese addresses I found involved in spam relatively recently. In each case, as soon as the trace hit Chinese address space, the routers had no rDNS at all - not just mismatched with forward DNS, but no names in sight. Lists aliases in the sense of returning multiple PTRs, or in the sense of passing through a CNAME? If the former, do the other names also forward-resolve to the address in question? /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B

Then why aren't all the hosts I see no rDNS for in China nullrouted? I think you missed the "de-facto" part of what I said. What you said sounds like a de-jure requirement, and anyone hwo actually looks for rDNS many places will see that there is no such de-facto requirement. And, it would have to be ICANN; ARIN has no jurisdiction outside North America. In practice, it simply isn't enforced - witness China - which is why I say that de-facto it's nonexistent at present. Then why aren't they nullrouted? This comes back to the difference between the de-jure rqeuirement you cite and the observance of current reality, which is that there is no such requirement in practice. As additional PTR records, or as names to which CNAMEs, pointing to the real PTR-owning names, are attached? Either one could reasonably be called aliases, and there is a huge difference. Now I'm confused. I can't figure out what you're describing. The only RFC I'm aware of that could be behind the "RFC sanctioned mechanism" is 2317, but that one describes the CNAME way, and nobody competent enough to get that right is likely to put in A records for the intermediate CNAMEs. What is the address of the mailhost in question? That way I can just poke at the DNS and see what's really there.... /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B