NFS Performance, concluded

Back in the middle of last year I wrote about our plans to tackle our NFS performance issues by introducing a direct and dedicated network link to carry our NFS traffic between the clients and the servers. We’d done the tests so we just had to implement it.

First we waited for the financial year (1 August) to roll over so we had some money, then we went and purchased 2 gigabit switches and 4 quad port network cards for the client machines. We only really needed dual port cards, but the supplier gave a choice of single or quad. The server nodes, which are part of our cluster, already had sufficient ports (8 per node, 6 of which are now used!).

You’d think it’d be pretty simple from there? It wasn’t. We hit a couple of snags:

1. How do we get the cables directly from one cabinet to another? All our cabling patches back to a central network cabinet, but we don’t have enough patch panel ports to send them all there and back.
2. What colour cables should we use? We can’t use the normal colour!

After much deliberation other jobs came along and consumed my time for the next few months.

So, a couple of months ago we took the plunge and made an important decision. We got blue cables. This would avoid confusion with our yellow cables (normal network), purple cables (crossover network), red cables (serial network), green cables (serial rolled) or grey cables (to be burnt alive). We also noticed some handy holes in the tops of the cabinets and neatly threaded the link cables to the servers through there.

With the hard work done we set about putting the new cards in to the client machines. The first machine was a good test case and I spent a while sorting our configuration and automounter setup to deal with the new link nicely. The remaining machines I’ve done on Tuesday mornings this month, with the last one being done today.

This leaves us with the important question. Is it actually quicker? My raw tests prove it is – ping times are halved and times to transfer large files are also halved. Loading my email in mutt is much quicker, as is listing my overly populated home directory.

Sorted then? Not quite – we still have a few users with Exmh slowdown problems. We’re still investigating that. Maybe Exmh is doing something pathalogically slow that doesn’t agree with NFS. Or maybe it’s just getting a bit slow in its twilight years. I’ll leave that to the boss (the only Exmh user in our group) to figure out 😉