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Surviving Slashdotting with a Small Server

Posted by michael on from the soon-to-be-an-oreilly-book dept.

S.BartFarst writes "Our little departmental server has been slashdotted twice in the last year and survived! Implementation of a two-headed redundant hardware scheme using linux virtual server and backup and failover capabilities enhanced by the linux high-availability tools has produced a nifty low-cost solution. Gotta love those little white boxes! (also having a university-supplied BIG PIPE doesn't hurt). More interesting is the documentation of the apparent exponentially decaying attention span of slashdotters. Anybody else observed similar phenomena?"

11 of 307 comments (clear)

  1. Clever, clever by Frodo2002 · · Score: 4, Insightful

    Notice this comment was posted on a slow Sunday afternoon (EST). Very clever, because they know that /.'ers can't resist a challenge like that. Feel sorry for them on Monday morning though...

  2. well golly gee... by JeanBaptiste · · Score: 5, Insightful
    (also having a university-supplied BIG PIPE doesn't hurt).


    well there you go... having a massive amount of bandwidth will allow you to survive a slashdotting. In most cases of slashdotting, I dont think the server was the bottleneck... its no problem for a server to dish out static pages... its the bandwidth, especially for serving pictures or videos....
    1. Re:well golly gee... by mo · · Score: 4, Insightful

      You're right. Bandwidth also serves a big purpose in finishing requests quickly. For example, let's see what happens when I have a 1.5mbps line with 512 concurrent requests. First of all, if you're using apache 1.3.X or 2.0 prefork, you've filled 2 gigs of ram by spawning 512 clients. Furthermore, you're bandwidth allocation per-client is 384 bytes/sec. This means you're spoon feeding your pages to your clients which makes it really hard for your server to get that 512 number down to something manageable.

      The problem here, is that the bandwidth bottleneck will make your server either (a) run out of processes/threads, (b) run out of ports/sockets, or (c) run out of memory from spawning all of the processes/threads to handle all of the stalled connections.

      Once this happens, people no longer can connect to you, and you're toast. The crazy thing here is that this can happen even at 10mbit/sec if you're machine is configured well enough, and if the content you're serving is large enough (IE: image/media serving).

      So cheers for these guys at keeping their bandwidth/server ratio high, I actually really like their architecture. But note that the greatest architecture in the world won't save you from a slashdotting if your server(s) are on a business dsl line.

    2. Re:well golly gee... by evilviper · · Score: 4, Insightful

      We aren't talking about an actual error, that's just what it is called.

      What we are talking about is sending a different, low-bandwidth page, which will reload the main page after a certain ammount of time.

      Sure, you aren't immediately serving up the page to everyone who is requesting it, but people will only see a delay of a minute or so, rather than the server not serving up anyone, and crashing and burning for a day before anyone resets the thing. Or maybe just saturating the line, so nobody gets anything faster than 0.00001kbps, which is far far worse than having to leave the error page open in the background a couple minutes before it has a chance to load the main page.

      --
      Slashdot gets worse every day... Pipedot: News for nerds, without the corporate slant
  3. Is it decaying attention span? by Eevee · · Score: 5, Insightful

    Or is it where the article is at any given time? Top of front page gives lots of hits. As it drifts down, the hits slow as fewer read; to the sidebar, fewer but still substantial hits; then off to the specialty pages such as Science or Games, then only a few will read.

    Of course, the only test would be to repost the article and see if there's the same number of hits... Nah, slashdot would never go for duplicate stories.

  4. That hits graph by KingDaveRa · · Score: 3, Insightful

    Interesting how it peaks, drops off slowly then rises again a little before dropping off again. Maybe some 'behind the curve' slashdot readers?

  5. You didn't get Slashdotted by 0x0d0a · · Score: 4, Insightful

    You didn't get Slashdotted if the server was still operating normally. You just had some people from Slashdot visit.

    --
    May we never see th
  6. Re:Third Time's a Charm? by BWJones · · Score: 5, Insightful

    Our little departmental server has been slashdotted twice in the last year and survived!

    Oh, come on. Even my little old G3 iMac is capable of handling quite a load from Slashdot and this site is serving up graphics intensive stuff. What you need to prevent a good Slashdotting is bandwidth that universities provide. T3 backbone connections are a wonderful thing. :-)

    Go ahead click all you want.

    --
    Visit Jonesblog and say hello.
  7. Re:Third Time's a Charm? by Anonymous Coward · · Score: 3, Insightful
    a friend of mine had his site featured on the front page of slashdot without any problems. Page hits spiked for a couple days, but his setup (P4 x86 linux box, apache, busines DSL) handled it fine. And, after being hit he discovered his bandwidth was being capped too low by his ISP :).

    Most slashdottings come from limited bandwidth or php/perl/asp/mysql/ etc being unable to handle it. Most dynamic content could be static content. (Most slashdot pages are static caches).

  8. Re:Wouldn't you need an expensive switch? by PurpleFloyd · · Score: 3, Insightful
    Assuming the page was fairly small, without lots of pictures or movies, I'd imagine that a small 10/100 switch would handle the load fairly well.

    On the stats link provided for a January slashdotting, the most bandwidth used in a day was a little under 7.4 GB. Assume that it was posted on /. at noon, so there were 12 hours to spread the big hit over: about 617 MB/hr. That's a little over 10 MB/Min, or 170 KB/sec. Even if we assume that the initial hit was double that, I can easily stream a 1000 KB/sec Divx movie over my 100 Mbps switched home LAN. The limiting factors here are the servers, routers and bandwidth to the Internet, not the local network connecting the servers.

    --

    That's it. I'm no longer part of Team Sanity.
  9. Exponential decay by rjh · · Score: 4, Insightful

    Why is it surprising that it follows an exponential dropoff? The only interesting questions are the coefficients of exponential dropoff, not that it's exponential--I'd sit upright and take notice if it was a linear decrease.

    Anything which follows a steady fractional diminishment will have a curve of y = ke**-ax, where k and a are constants. You see this basic equasion pop up all the time in physics, economics, statistics... etc. Why should server slashdotting be any different?