Un-killable Processes : Red Hat Enterprise Linux

By Johnathan Kupferer, Red Hat Certified Engineer

Before Red Hat Enterprise Linux 4, there really wasn’t a good way to handle processes that had entered an
uninterruptible sleep waiting on an unresponsive NFS server. This was particularly frustrating because the
umount man page promises that “-f” will “Force unmount.” This allows an NFS-mounted filesystem to be
unmounted if the NFS server is “unreachable.” That was how it was supposed to work, with the caveat that
the filesystem must have originally been mounted with “soft” or “intr” options.Well, no more. Though the
man page doesn’t say so, umount -f now comes to the rescue and will unmount hard and uninterruptible
mounts.

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