On 2003.10.06 23:13, Steve Fosdick wrote: On 2003.10.06 22:30, MJ Ray wrote:
One tip: be very careful with NFS mount options. If a server hangs on you, then you can't just kill the thing and restart like you can with the userland amd. You could lose the whole autofs system for the duration unless you have timeouts and interruptable options. Any process trying to touch it will block hard, leading to amusingly high load averages (I think around 120 was my highest before fixing it...).
Futhermore if you enable use the intr option so any blocked processes can be killed, then killing one of them can cause a kernel oops on the client.
Specifically, imagine you have a process that has a file open but has removed the directory entry for that file. The normal way unix handles this is that the file will continue to exist anonymously until the last process closed it whereupon the file is deleted and the space recovered. On NFS, when the last directory entry to an open file is deleted the file actually gets renamed to a hidden filename. So, you have this process running and it's holding the file open but the NFS server has gone away and you want to unmount the filesystem so you kill the process at which point the kernel panics because it can't delete the hidden file on the NFS server.