October 2010 Archives

NFS Performance: Brain Teaser (Solved!)

After spending multiple hours trying to diagnose a performance issue with NFS in my lab, I've suddenly stumbled upon a situation in which I can honestly say, I'm completely bewildered.

When copying a 256MB test file to the NFS mount the transfer takes ~70 seconds, which equates to roughly 3.6MB/s, i.e. very slow. The client and sever hardware is modern and equipped with Gigabit NICs and an accompanying Gigabit switch. With this hardware I'd expect average transfer speeds of 30-40MB/s, with the hard drives being the bottleneck.

So here's where it gets strange...