On 11/29/2016 07:37 AM, Tom Horsley wrote: > On Tue, 29 Nov 2016 10:05:15 -0500 > bruce wrote: > >> On the clientside easy enough to automate a process/logic to every so >> often do a umount/remount process on the individual client. > > That will work, but it is pretty heavy handed, and "umount -l" > is almost always necessary because something, somewhere, on the > system is always referencing the remote file and it will refuse > a normal "umount" (and umount -f has to time out for hours before > it forces the unmount). > > I get this crap all them time when a symlink changes on the > server, and the client doesn't see the change (which isn't supposed > to be a problem, but is). Usually removing the symlink, doing > an "ls -lL' on the client to convince it that it is gone, > then recreating it on the server works. > > I've never been able to understand how it is that NFS is so > widely used, yet so broken. You have to stop expecting a NAS (network attached storage) volume to behave like a local device. It is a completely independent device and not under control of your client's kernel. Many of the internal notification mechanisms you rely on simply aren't there because there is no way to implement them reliably (inotify, open file counts and such). Some of these things you don't even know you're using on a native volume. Look at the issues involved in sharing a file with read/write access among separate processes on the same machine. Now multiply that by a hundred, add in network latency issues and you'll see it's "a fine kettle of fish". A big cause of stale handles and such is due to the various client caches. Yes, the caches speed things up and can reduce network usage, but with these benefits come trade-offs. Because it's a cache and items can change on the server--either directly on the server or by other clients' activities--the client may find that the NAS has "changed" since the last time it updated its cache. That's the nature of NAS--be it NFS, CIFS, WebDAV, whatever. If you really can't tolerate these things, you can usually disable much of the client-side cache when the filesystem is mounted. You'll take a performance hit and you'll flog the network much harder, but the stale filehandle issue will be reduced. You won't eliminate it, but it'll be better. ---------------------------------------------------------------------- - Rick Stevens, Systems Engineer, AllDigital ricks@xxxxxxxxxxxxxx - - AIM/Skype: therps2 ICQ: 226437340 Yahoo: origrps2 - - - ---------------------------------------------------------------------- _______________________________________________ users mailing list -- users@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to users-leave@xxxxxxxxxxxxxxxxxxxxxxx
