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Description of problem:
It appears that the netfs script was written with the intention to
gracefully stop (unmount) NFS file systems. The problem is that the
first thing the script does is forcibly unmount the NFS-mounted file
systems. As a result, it is unable to terminate any processes that
have files open on those file systems. On our servers -- where we use
NFS extensively -- this leaves hundreds of processes "stuck" because
NFS was pulled out from under them, and the servers fail to shutdown
properly, usually requiring a power cycle.
We've patched the netfs script so that it gracefully stops all
processes with open files on NFS-mounted file systems. It makes four
attempts (sending the following signals in this order: HUP, TERM,
KILL, KILL) before forcing the umount. Test shows that it works as
expected, and our servers shutdown quickly. I'll include the patch as
soon as I can figure out where to upload it.
Version-Release number of selected component (if applicable):
Steps to Reproduce:
1. Start a process that opens a file on an NFS-mounted file system.
2. Shutdown system
Actual Results: System hangs on shutdown.
Expected Results: System should have shutdown quickly and not
required a power cycle.
Created attachment 110205 [details]
Patch to fix NFS umount bug in /etc/init.d/netfs
This problem is being considered for the next release of Red Hat Enterprise
Linux. Red Hat does not currently plan to provide a resolution for this in a Red
Hat Enterprise Linux update for currently deployed systems.
With the goal of minimizing risk of change for deployed systems, and in response
to customer and partner requirements, Red Hat takes a conservative approach when
evaluating changes for inclusion in maintenance updates for currently deployed
products. The primary objectives of update releases are to enable new hardware
platform support and to resolve critical defects.