VirtualBox Ubuntu Slow Shared Folders Under Windows

Often, especially with large file transfers, it seems that the shared folders facility in VirtualBox (running Ubuntu, but not sure that matters), running as a Windows guest, are very slow.

I added these lines

255.255.255.255        VBOXSVR #PRE
255.255.255.255        VBOXSRV #PRE

To this file:

\windows\system32\drivers\etc\lmhosts

And then restarted the VM. I saw a big improvement.

Shared Folders Issue on VirtualBox Ubuntu

I recently upgraded my VirtualBox Guest Editions to 4.3.10 and the shared mounts that I normally create stopped working. I was running this mount:

sudo mount -t vboxsf Dropbox /home/steve/Dropbox

And getting this error:

mount: wrong fs type, bad option, bad superblock on /home/steve/Dropbox,
missing codepage or helper program, or other error
In some cases useful info is found in syslog - try
dmesg | tail  ...

After some research, it turns out that after the Guest Editions upgrade, the symlink for mount.vboxsf was broken. Here's what I ran to correct it:

cd /sbin
sudo rm mount.vboxsf
sudo ln /usr/lib/x86_64-linux-gnu/VBoxGuestAdditions/mount.vboxsf mount.vboxsf

This did the trick. Thanks to this post for the tip:

http://superuser.com/questions/736024/cannot-share-host-directory-with-virtualbox-guest-mint-16-64-bit

UPDATE: this may be fixed in the next Guest Editions release:

https://www.virtualbox.org/ticket/12879