the install for an operating system on a gridcolo virtual machine is a long running process that is started by clicking on a link. this is one way to kick off a long-running process in rails.

  def install_os(distro)
    raise "install on non-root partition attempted." if !root_mount?
    raise "installation already in progress" if install_progressing?
    self.distro = "* installing #{distro}"
    self.save!
    sys="#{RAILS_ROOT}/script/runner " +
         "\"DiskPartition.install_os(#{self.id},\'#{distro}\')\" &"
    unix_shell(sys)
  end

  def self.install_os(id, distro)
    dp = DiskPartition.find(id)
    raise "installation already in progress" if dp.install_progressing?
    sys = "ssh #{dp.box.hostname} "+
          "/usr/local/bin/gc_install.sh #{dp.mount_code} #{distro}"
    unix_shell(sys) or raise "OS install failed for distro #{distro} " +
                             "on mount #{mount_code} on box #{box.id}"
    dp.distro = "#{distro}"
    dp.save!
  end

that gets the process started, and leaves an indication that the process is in motion.