How to use automount daemon (amd)
on at cs.ait.ac.th
Thu Aug 28 05:19:11 UTC 2008
I have the following issue with amd.
I want to write a script that will detect whenever a USB disk is
plugged in and then run a backup.
My configuration is described below.
mount:="/usr/local/sbin/fsck_mount fsck_mount /automnt/da0";\
unmount:="/usr/local/sbin/spin_down spin_down /automnt/da0"
where fsck_mount is a short script that does a fsck_ffs -p, to catch
unclean file system) then a mount and spin_down a script that does
umount then camcrontrol stop.
/dev/da0s1d /automnt/da0 ufs rw,noauto 0 0
And amd runs with the parameters:
/usr/sbin/amd -p -a /.amd_mnt -l syslog /host /etc/amd.map
When I play with mounting and dismounting the USB disk by hand, it
- I attach the USB disk, wait for usbd to detect umass and create the
- I access to /host/localhost/da0
- I launch my backup by hand.
- I amq -u /host/localhost/da0 to umount the disk da0
- I remove the USB drive.
All this is OK.
But I would like my backup script to be able to check whether the USB
disk is present or not.
If I try to access /host/localhost/da0 while the USB disk is not
attached, I get no error (ls /host/localhost/da0 returns empty).
Then I attach the USB disk and wait for it to start. Then try to ls
again but it still gives me nothing. Mount will not show that
/automnt/da0 is mounted.
It seems that if I try to access /host/localhost/da0 when there is no
corresponding disk, amd remembers that error and refuse to mount the
disk later until the cache is cleared.
The command amq -m shows:
"root" amanda:(pid1290) root 1 localhost is up
/etc/amd.map /host toplvl 1 localhost is up
/etc/amd.map /host/localhost auto 1 localhost is up
fsck_mount /automnt/da0 /automnt/da0 program 1 localhost is up
where /automnt/da0 seems to be mounted even when there is no such
I think that if my backup script tries to check /host/localhost/da0
with a period (every 10 minutes) greater than amd cache timeout
(default 5 minutes), then it should be able to detect when the disk is
mounted the next time.
I could reduce the cache time out too, but that may interfeer with the
efficiency of amd.
I wonder if there is a different way to check that the disk is
available, than trying to ls /host/localhost/da0.
A side question about rpcbind.
I'd like to start rpcbind to bind only to localhost. I tried:
/usr/sbin/rpcbind -h 127.0.0.1
which works but with the error:
rpcbind: cannot bind 127.0.0.1 on udp: Address already in use
Is there a way to start rpcbind on localhost only?
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