On 05/19/2016 05:27 AM, Tom H wrote:
1) Can your monitoring software be taught that /home and /export/home
are the same?
Not easily as far as I know. It just relies on what the agent reports,
and the agent just shows what this command outputs:
excludefs="-x smbfs -x cifs -x iso9660 -x udf -x nfsv4 -x nfs -x mvfs -x
zfs"
df -PTlk $excludefs | sed 1d
2) There was a problem with the earlier implementation of "/etc/mtab"
in that you could
mount /dev/sdb1 /path/to/mount
mount -o bind /path/to/mount /path/to/bind-mount
umount /path/to/mount
and still have "/path/to/bind-mount" tagged as "bind" in "/etc/mtab"
because, from the kernel's perspective, running
mount /dev/sdb1 /path/to/mount
mount -o bind /path/to/mount /path/to/bind-mount
is the same as running
mount /dev/sdb1 /path/to/mount
mount /dev/sdb1 /path/to/bind-mount
so "/etc/mtab" was turned into a symlink to "/proc/self/mounts". It's
even become a requirement in systemd but I've forgotten with which
version.
3) An ex-colleague pointed out to me yesterday that one of the reasons
for choosing the shortest path was that otherwise "/rootfs" or
"/newroot" might show up in df rather than "/" if the "first local
mount" had been chosen. He must have been referring to the old
"/dev/root" symlink, but maybe he's right!
Near as I can tell bind mounts are no longer in use. There is
definitely situations where a local filesystem is mounted as normal on a
local mountpoint and also via NFS and the automounter on another
mountpoint but there's nothing to indicate it's a bind mount. I believe
I used to be able to add "-x bind" to the df command and it would only
show local mount points even if both exist. As far as I know there's no
way to define an automount to do NFS if a filesystem is remote, or a
bind mount if it's local.
--
Stephen Berg
Systems Administrator
NRL Code: 7320
Office: 228-688-5738
stephen.berg....@nrlssc.navy.mil
