Date: Wed, 21 Feb 2001 21:06:35 -0500 From: Allen Landsidel <all@biosys.net> To: stable@FreeBSD.ORG Subject: Re: cvsup confusion Message-ID: <4.3.2.7.2.20010221203901.00c8fd48@64.7.7.83> In-Reply-To: <200102211707.f1LH7Tj18877@vashon.polstra.com> References: <4.3.2.7.2.20010221054413.00c443a0@64.7.7.83> <4.3.2.7.2.20010221054413.00c443a0@64.7.7.83>
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At 09:07 2/21/2001 -0800, you wrote: >There is a problem with this approach. Suppose everybody did it that >way. Then at exactly the same time each week, everybody in a given >time zone would be trying to CVSup from their nearby mirrors. The >mirrors would quickly fill up, and you'd be retrying for hours, along >with everybody else in your time zone. That starts off around a "probably true" and progresses on to "nearly ludicrous." ;) 1. The higher you go in bandwidth (to end-users), the less users that have that kind of bandwidth. While the possibility of the mirrors getting congested is certainly possible, it's just as improbable. Let Y be the number of cvsup mirrors in the US, and X be the number of freebsd boxes in the US. Now, X/Y is the ratio of freebsd boxes to cvsup mirrors. It doesn't take a rocket scientist to determine that number will be ridiculously overburdened, probably in the neighborhood of a quarter million to one (NOTE: I'm totally pulling that number out of my ass, but it doesn't seem too unreasonable. As of Jan. 2001, out of 27 million sites checked, 15 million were running apache. 250k of them being freebsd would mean about 1 in 60 are freebsd.. I expect that number is probably higher.). With 250,000 estimated sites cvsupping to each server, If each server was assigned a unique time to (just begin) it's cvsup, spaced one hour apart, it would take 28 years for each server to cvsup just once. This is obviously not the case. Possible explainations are that I've overestimated the number of machines cvsupping (just 10k machines though would take over a year); that the machines cvsupping, in general, have far less bandwidth than the machines running the cvsup mirrors; etc. The bottom line of this explaination is simple. If every machine running freebsd was also cvsupping, it wouldn't matter -what- time they decided to do it at, the servers would be under full load constantly.. so saying "if everyone in one timezone did that, it would drag the server down" is a moot point. The servers do get dragged down, but if you'll notice, in general the lower numbered mirror you go with, the slower it is, almost any time of day, on any day of the month. People are just too lazy to pick a mirror thats close to them, or further down the "cvsupit" list than the first one they see. >It's much better to pick a random time and put it in your crontab. I disagree. I think it would be "much better" if this was truly a concern, to change the time that your periodics are executed, or to simply pick a different mirror that isn't saturated when your default periodic runs. ... In any case, to the original poster, regardless of how you decide to schedule your updates, you'll alleviate the problem by doing as was suggested and reading the manpage, or (a better solution imho, but reading the manpage anyway is always a great idea) condensing the three seperate cvsupfiles you have into one and only invoking one copy of cvsup to begin with. -------signature file------- PGP Key Fingerprint: 446B 7718 B219 9F1E 43DD 8E4A 6BE9 D739 CCC5 7FD7 "I don't think [Linux] will be very successful in the long run." "My experience and some of my friends' experience is that Linux is quite unreliable. Microsoft is really unreliable but Linux is worse." -Ken Thompson, Interview May 1999. http://www.freebsd.org FreeBSD - The Power to Serve http://www.rfnj.org Radio Free New Jersey - 375 streams - 96kbps @ 44.1khz http://namespace.org -- http://name.space Resist the ICANN! Support name.space! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-stable" in the body of the message
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