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And You Thought You Had a Big Database

  • May 1, 2008 at 1:33 pm

    #809796

    The only real purpose that I've seen for hubs these days is one that you can put in to promiscuous mode and use as a traffic sniffer. Everything these days should be switched at the desktop level and routed above that. Yeah, you can get hubs really cheap, but they're not worth it for busy traffic. Ignoring the fact that everyone sees everyone else's traffic, the big problem is bandwidth. Let's say you have a ten megabit hub with ten users on it. Bandwidth is shared, so each user gets, effectively, 1 megabit bandwidth. Make that 20 users, half a meg. 40 users, 256k. Etc. A switch gives each person a (seemingly) personal link between their PC and whatever host they need to talk to, the switch (and any upstream routers) make it appear that there are only the two hosts on the network. Each user gets the theoretical bandwidth max.

    If you ever have the time, I recommend that any SQL Server DBA study the Cisco CCNA program (Certified Network Associate): it is fascinating stuff to learn how the network actually works. Learning how DHCP and DNS works is cool stuff.

    What this has to do with terabyte databases I don't know, my biggest active is only about 15 gig, my biggest GIS database of raster images is around 150 gig. It'll be a while before we're in the TB league.

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    [font="Arial"]Knowledge is of two kinds. We know a subject ourselves or we know where we can find information upon it. --Samuel Johnson[/font]

  • May 1, 2008 at 3:17 pm

    #809834

    Thanks Wayne. You have it on several points.

    I was thinking of bandwidth more than security.

    A switch gives each person a (seemingly) personal link between their PC and whatever host they need to talk to, the switch (and any upstream routers) make it appear that there are only the two hosts on the network. Each user gets the theoretical bandwidth max.

    That's the N+1 or even N+2. A 4 port switch, like the one I cary in my laptop bag, has 5 or 6 channels.

    The whole hub vs switch started in response to Will and his problem of pushing large .bak files around. Also to point out that what you think might be the performance bottleneck in a system might not be the actual cause. They thought my issue was with the number of hubs when my issue was with hubs in the first place.

    ATBCharles Kincaid

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