On Tue, Jul 15, 2008 at 11:34 AM, Andrew Bell <andrew.bell.ia@xxxxxxxxx> wrote: > Hi, > > I have a RHEL 5 system that exhibits less than wonderful performance > when copying large files from/to an NFS filesystem. When the copy is > taking place, other access to the filesystem is painfully slow. I > would like to have the filesystem react well to small requests while a > large request is taking place. > > A couple of questions: > > Is this a reasonable expectation? Yes, but Linux NFS can't fulfill it. :-) There is currently only one RPC transport socket between client and server for each mount point. Large file copies (or similar operations) will queue a lot of I/O, so your small requests will take a while to get through the queued up writes or reads ahead of them. > Is this perhaps an I/O scheduling issue that isn't specific to NFS, > but shows up there because of the latency of my NFS setup? > > Is this most likely a client issue, a server issue or a combination? Well, if your server or network is slow, this kind of thing is more likely to happen. > Do you have recomendations on the best way to determine what is > happening? Are there existing tools to monitor active IO/NFS > requests/responses and any relevant queues? Yes, I wrote some Python tools that are still undocumented (ie you will likely have to read the Python source to figure out what they do). They were recently included in nfs-utils, but you can download them from: http://oss.oracle.com/~cel/linux-2.6/2.6.25/nfs-iostat and http://oss.oracle.com/~cel/linux-2.6/2.6.25/mountstats > > > Thanks for any info/ideas before I get in too deep :) > > -- > Andrew Bell > andrew.bell.ia@xxxxxxxxx -- Chuck Lever -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
