/net can be evil

I've written before about what a fan I am of the automounter. However the curse of the automounter is laziness. Direct mounts I covered but the next topic is the “/net” mount point.

Like direct automount points “/net” has it's uses, however when it is used without thought it is evil. The thing that has to be thought about is that “/net” quickly leads you into some of the eight fallacies of distributed computing: which I reproduce here from Geoff Arnold's blog:

Essentially everyone, when they first build a distributed application, makes the following eight assumptions. All prove to be false in the long run and all cause big trouble and painful learning experiences.
  1. The network is reliable
  2. Latency is zero
  3. Bandwidth is infinite
  4. The network is secure
  5. Topology doesn’t change
  6. There is one administrator
  7. Transport cost is zero
  8. The network is homogeneous

Now since when using “/net” you are just a user not a developer that cuts you some slack with me. However if you are a engineer looking at crash dumps that are many gigabytes via “/net” or uploading from a local tape to and from an NFS server on the other side of the world, or even close but over a WAN, you need to be aware of fallacies 1,2,3 and 7. Then wonder if there is a better way, invariably there is a faster, less resource hungry way to do this if you can login to a system closer to the NFS server.

If that is the case then you should get yourself acquainted some of the options to ssh(1). Specifically compression, X11 forwarding and for the more adventurous agent forwarding.



Comments:

I once went to a rather lengthy seminar that a guy was giving about his research work. The work was essentially an improved replacement for TCP so as to lower the number of collisions. This guy was a mathematician and it was quite clear rather soon that he had no real clue about computers or had been anywhere near a real network. His improved model relied on some rather special assimptions: 1) All nodes share a single medium. This isn't too bad if you think about wireless 2) All nodes can see each other all the time. Ooops, suddenly any applications for wireless have gone out of the window. 3) The transmission time, latency, between any two node is zero. Oops, there goes the real world. He was intending to look at implementing this thing in the real world, and this was a year ago, so it would be interesting to see how far he got. I suspect that the answer is not very.

Posted by inomine on July 15, 2007 at 09:57 AM BST #

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This is the old blog of Chris Gerhard. It has mostly moved to http://chrisgerhard.wordpress.com

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