It’s a long known issue that VirtualBox shared folder performance degrades quickly as the number of files in the shared folder increases. As a project reaches 1000+ files, doing simple things like running unit tests or even just running an app server can be many orders of magnitude slower than on a native filesystem (e.g. from 5 seconds to over 5 minutes).
If you’re seeing this sort of performance drop-off in your shared folders, NFS shared folders can offer a solution. Vagrant will orchestrate the configuration of the NFS server on the host and will mount of the folder on the guest for you.
Note: NFS is not supported on Windows hosts. According to VirtualBox, shared folders on Windows shouldn’t suffer the same performance penalties as on unix-based systems. If this is not true, feel free to use our support channels and maybe we can help you out.
John and I did extensive benchmarks using various solutions for the VirtualBox shared folder performance issue. These benchmarks were run on a real-world rails project with a test suite of over 6000 tests. We ran a single unit test file and timed the average of several runs:
VirtualBox Shared Folders: 5m 14s Host File System: 10s Native VM File System: 13s NFS Shared Folders: 22s NFS Shared Folders (warm cache): 14s
As you can see, while there is a small performance hit compared to having the files natively on the VM, it is perfectly reasonable versus true VirtualBox shared folders.
Notice the last line marked with “(warm cache).” During our daily usage testing, we noticed that NFS really shines when many inodes of the host filesystem are cached on the VM. Since in real world applications, only a few files change at a time, we found that we were able to experience nearly native VM file system performance throughout the day.
Before enabling NFS shared folders, there are two main requirements:
nfsdinstalled, the NFS server daemon. This comes pre-installed on Mac OS X 10.5+ (Leopard and higher), and is typically a simple package install away on Linux systems.
Vagrant must edit system files on the host in order to configure NFS.
Therefore, at some point during the
vagrant up sequence,
you will be prompted by your system for administrator privileges (via
Vagrant modifies the
/etc/exports file. Any previously
set exported folders will be preserved. While Vagrant is heavily tested,
the maintainers take no responsibility in any lost data in these files.
NFS shared folders are very easily enabled through the Vagrantfile configuration by setting a flag on the
config.vm.share_folder method. The example below uses NFS shared folders for the main project directory:
Vagrant::Config.run do |config| config.vm.share_folder("v-root", "/vagrant", ".", :nfs => true) end
:nfs flag causes that folder to be mounted via NFS.