On Tue, 2006-07-11 at 14:00 -0500, Gregory Baker wrote: > We have thousands of linux clients hitting netapp file servers (many > 3500 series, clustered) on a local gigabit LAN. From time to time, > applications return "file not found" when attempting to automount a > directory and access a file. An example of this is a long running > process, which reads in data, processes it for hours (in which time the > filesystem is unmounted) then tries to read more data from that mount > point (which causes a "file not found" error in the application). This > occurs about 1/100th of the time. > > Researching at Netapp turns up this bit by Chuck Lever (Linux NFS > contributer) > > "Using the Linux NFS Client with Network Appliance Filers" > http://www.netapp.com/libr ary/tr/3183.pdf (February 2006) > > page 10 says... > > "Due to a bug in the mount command, the default retransmission timeout > value on Linux for NFS over TCP is quite small...To obtain standard > behavior, we strongly recommend using "timeo=600, retrans=2" explicitly > when mounting via TCP." > > Our defaults (assuming man pages are correct, RedHat Enterprise Linux 3) > would be timeo=7, retrans=3, which translates to 7+14+28+56 = 105 tenths > of a second (10 seconds). It appears netapp is suggesting waiting > 600+600 = 1200 tenths (120 seconds) before giving up on the mount command...
No they are not. See below. > * What "bug" in the mount command do you believe NetApp is talking about? It has nothing to do with the mount timeout: Chuck is talking about the retransmission timeout for TCP connections 'timeo' which should indeed be set to a high value since TCP guarantees message delivery (unlike UDP which requires a small timeo value). Setting it too low means that you end up spamming your server with a load of unnecessary retransmissions. This was indeed the case for some older versions of 'mount' and also for older versions of the am-utils/amd automounters. > * What do you think proper options for NFS auto/mounts would be for > extremely busy centralized NFS filers? Something like mount -t nfs -ohard,timeo=600,retrans=2,rsize=32768,wsize=32768,tcp foo:/ /bar should be a fairly safe bet. You might want to add the 'intr' flag too, depending on how you feel about the behaviour w.r.t. pressing ^C. > * What is the reference standard behavior? To which reference are you referring? Cheers, Trond _______________________________________________ autofs mailing list [email protected] http://linux.kernel.org/mailman/listinfo/autofs
