Here's some more details: I think Alsa should do all its disk operations only when all the disks are fully mounted. Else you will have race conditions, and leave artifacts which you cannot find later.
# df|egrep /$\|/var /dev/sda8 6374088 4297552 1734696 72% / /dev/sda7 5333357 2415393 2642466 48% /var # mount /dev/sda8 /mnt/usb/thumb/ # find /mnt/usb/thumb/var/ ! -type d -ls 326072 0 lrwxrwxrwx 1 root root 23 Sep 25 19:57 /mnt/usb/thumb/var/run/alsa/.config/pulse/583e5eeffd5b64952b92010045b373b0-runtime -> /tmp/pulse-PKdhtXMmr18n # rm -vr /mnt/usb/thumb/var/run removed ‘/mnt/usb/thumb/var/run/alsa/.config/pulse/583e5eeffd5b64952b92010045b373b0-runtime’ removed directory: ‘/mnt/usb/thumb/var/run/alsa/.config/pulse’ removed directory: ‘/mnt/usb/thumb/var/run/alsa/.config’ removed directory: ‘/mnt/usb/thumb/var/run/alsa’ removed directory: ‘/mnt/usb/thumb/var/run’ So on shutdown be sure to write before unmounting starts, and on boot read after all mounting ends.