Re: NFS client permanent mount points under /mnt?

[Malcolm Herbert <mjch%mjch.net@localhost>]

On Sun, Jul 28, 2019 at 04:55:15PM +0930, Brett Lymn wrote:
|On Thu, Jul 25, 2019 at 08:02:34PM -0400, Greg Troxel wrote:
|> /mnt is for random use, when you have some unexpected drive and want
|> to use it. People who know tradition would be very surprised at
|> /mnt/nfs/host. So do not use /mnt.
|
|agreed, don't use /mnt, unfortunately linux does. I have shot myself in
|the foot many a time when doing a rescue, mount something on /mnt and
|then the rescue collapses because they built a mount tree under /mnt
|that I just covered up... gah

Solaris typically mounts the system being installed/rescued under /a for
this exact reason ...

|> I see your point about things deep in the hierarchy, but it's far
|> saner to mount the system or part of it, and symlink in. If you had
|> the disk from the system and mounted it, that's what you'd do.
|
|I don't agree with this - creating sym links can lead to a bunch of
|dangling sym links all over your file system, they can be hard to track
|down so messy to clean up. Much better to mount the fs where it is
|supposed to be in the first place. Also, to be nit-picky there is a
|performance impact from a sym link, the link is read every time it is
|traversed so you double your reads on a path traversal for every sym
|link.

I second this - I once inherited a site ($JOB-3) where (for some
non-obvious reasons) our Irix fleet depended upon a symlink hanging off
the NFS share from a central Linux box that pointed back to their own
local filesystem(!!) ... that was a fun one to sort out when we had a
hiccup with our main fileserver as they all just ... stopped ...

since then I've been a fan of mounting a filesystem somewhere out of the
way and then null/bind mounting where I actually need the content ...
makes things nice and explicit and easily discoverable ... this was back
in the day before LVM and ZFS with their pool-based model, so really the
only option to managing free space was sometimes to migrate data between
large filesystems and altering the relevant mounts ... the users were
none the wiser once that had completed ... and the nice thing was that I
couldn't unmount whilst anyone was using it, whereas with a symlink you
might not notice that it's changed

that said, sometimes unexpected mount ordering can ruin your day,
especially when there's something like ZFS in the mix, which does
its mounts outside of the usual 'mount -a' scope ... yes, one can flag
particular filesystems as 'mountpoint=legacy' which means they get
mounted from /etc/fstab, but that's ... hacky (and ZFS needs to be
explicitly enabled for bind mounts under Linux anyway)

Regards,
Malcolm

-- 
Malcolm Herbert
mjch%mjch.net@localhost