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Every developer wants both fast startup of the environment and quick response to web page requests. DDEV-Local is always focused on improving this. However, both Docker Desktop for Windows and Docker Desktop for Mac have significant performance problems with mounted filesystems (like the mounted project where code can be edited either inside the container or on the host).

Freeing Up System Resources

Every project you run uses system resources, and may compete for those resources. A reasonable practice is to stop projects that aren't currently in use, or stop all projects with ddev poweroff and then start the one that you're actually working on. ddev list will show you the projects you're working on.

Docker Desktop for Mac Settings

Docker Desktop for Mac has a number of settings that you'll want to pay attention to. Under "Advanced" in the "Resources" section in "Preferences", you can adjust the amount of memory, disk, and CPUs allocated to Docker. While the defaults work well for a small project or two, you may want to adjust these upward based on your experience. The default memory allocation is 2GB, but many people raise it to 4-5GB or even higher. The disk allocation almost always needs to be raised to accommodate increased downloaded images. Your experience will determine what to do with CPUs.

Using NFS to Mount the Project into the Web Container

NFS (Network File System) is a classic, mature Unix technique to mount a filesystem from one device to another. It provides significantly improved webserver performance on macOS and Windows. DDEV-Local supports this technique, but it does requires a small amount of pre-configuration on your host computer. DDEV-Local doesn't make changes to your computer's configuration without your involvement and approval, so this is done with a setup script that you run and that asks you for your sudo password.

The steps to set up NFS mounting on any operating system are:

  1. Make sure DDEV-Local is already working and you can use it.
  2. Configure the NFS server and exports files using the provided scripts for each operating system.
  3. Test that NFS is working correctly by using ddev debug nfsmount in a project directory. The first line should report something like "Successfully accessed NFS mount of /path/to/project"
  4. Enable NFS mounting globally with ddev config global --nfs-mount-enabled (You can also configure NFS mounting on a per-project basis with ddev config --nfs-mount-enabled in the project directory, but this is unusual. If nfs mounting is turned on globally it overrides any local project settings for NFS.)
  5. ddev start your project and make sure it works OK. Use ddev describe to verify that NFS mounting is being used. The NFS status is near the top of the output of ddev describe.

Note that you can use the NFS setup described for each operating system below (and the scripts provided) or you can set up NFS any way that works for you. For example, if you're already using NFS with vagrant on macOS,and you already have a number of exports, the default export here (your home directory) won't work, because you'll have overlaps in your /etc/exports. Or on Windows, you may want to use an NFS server other than Winnfsd, for example the Allegro NFS Server. The setups provided below and the scripts provided below are only intended to get you started if you don't already use NFS.

Note that NFS does not really add to performance on Linux, so it is not recommended.

macOS NFS Setup

Download, inspect, make executable, and run the script. Use curl -O && chmod +x && ./ This stops running ddev projects, adds your home directory to the /etc/exports config file that nfsd uses, and enables nfsd to run on your computer. This is a one-time setup. Note that this shares your home directory via NFS to any NFS client on your computer, so it's critical to consider security issues; It's easy to make the shares in /etc/exports more limited as well, as long as they don't overlap (NFS doesn't allow overlapping exports).

If your DDEV-Local projects are set up outside your home directory, you'll need to edit /etc/exports to add a line for that share as well.
sudo vi /etc/exports and copy the line the script has just created (/System/Volumes/Data/Users/username -alldirs -mapall=<your_user_id>:20 localhost), editing it with the additional path, e.g: /Volumes/SomeExternalDrive -alldirs -mapall=<your_uid>:20 localhost.

Warning: You may need to temporarily give your terminal "Full disk access" before you (or the script provided) can edit /etc/exports. The basic idea is that in the System Preferences -> Security and Privacy -> Privacy you need to give "Full Disk Access" permissions to your terminal app. Note that the "Full Disk Access" privilege is only needed when the /etc/exports file is being edited by you, usually a one-time event. (Note that in more recent versions of macOS a prompt will do this automatically and temporarily for you.)

Warning: If the projects are in a subdirectory of the ~/Documents directory or on an external drive, it is necessary to grant the "Full Disk Access" permission to the /sbin/nfsd binary. Full details are below.

Windows NFS Setup

The executable components required for Windows NFS (winnfsd and nssm) are packaged with the ddev_windows_installer in each release, so if you've used the windows installer, they're available already. To enable winnfsd as a service, please download, inspect and run the script "" installed by the installer in \Program Files\ddev\ (or download from in a git-bash session on windows. If your DDEV-Local projects are set up outside your home directory, you'll need to edit the ~/.ddev/nfs_exports.txt created by the script and then restart the service with sudo nssm restart nfsd.

Firewall issues: On Windows 10 you will likely run afoul of the Windows Defender Firewall, and it will be necessary to allow winnfsd to bypass it. If you're getting a timeout with no information after ddev start, try going to "Windows Defender Firewall" -> "Allow an app or feature through Windows Defender Firewall", "Change Settings", "Allow another app". Then choose C:\Program Files\ddev\winnfsd.exe, assuming that's where winnfsd is installed.

Also see the debugging section below, and the special Windows debugging section.

Debugging ddev start failures with nfs_mount_enabled: true

There are a number of reasons that the NFS mount can fail on ddev start:

  • Firewall issues
  • NFS Server not running
  • Trying to start more than one NFS server.
  • NFS exports overlap. This is typically an issue if you've had another NFS client setup (like vagrant). You'll need to reconfigure your exports paths so they don't overlap.
  • Path of project not shared in /etc/exports (or ~/.ddev/nfs_exports.txt on Windows)
  • Project is in the ~/Documents directory or an external drive on macOS Catalina or higher (see macOS information below)

Tools to debug and solve permission problems:

  • Try ddev debug nfsmount in a project directory to see if basic NFS mounting is working. If that works, it's likely that everything else will.
  • When debugging, please do ddev restart in between each change. Otherwise, you can have stale mounts inside the container and you'll miss any benefit you may find in the debugging process.
  • Inspect the /etc/exports (or ~/.ddev/nfs_exports.txt on Windows).
  • Restart the server (sudo nfsd restart on macOS, sudo nssm restart nfsd on Windows).
  • showmount -e on macOS will show the shared mounts.

macOS Full Disk Access for Special Directories

  • If you are on macOS, and your projects are in a subdirectory of the ~/Documents or ~/Desktop directories or on an external drive, you must grant "Full Disk Access" privilege to /sbin/nfsd in the Privacy settings in the System Preferences. On the "Full disk access" section, click the "+" and add /sbin/nfsd as shown here: screenshot
    You should then see nfsd in the list as shown:
  • sudo nfsd restart
  • Use ddev debug nfsmount in a project directory to make sure it gives successful output like
    $ ddev debug nfsmount
    Successfully accessed NFS mount of /Users/rfay/workspace/d8composer
    TARGET    SOURCE                                                FSTYPE OPTIONS
    /nfsmount :/System/Volumes/Data/Users/rfay/workspace/d8composer nfs    rw,relatime,vers=3,rsize=65536,wsize=65536,namlen=255,hard,nolock,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=,mountvers=3,mountproto=tcp,local_lock=all,addr=

macOS-specific NFS debugging

  • Please temporarily disable any firewall or VPN.
  • Use showmount -e to find out what is exported via NFS. If you don't see a parent of your project directory in there, then NFS can't work.
  • If nothing is showing, use nfsd checkexports and read carefully for errors
  • Use ps -ef | grep nfsd to make sure nfsd is running
  • Restart nfsd with sudo nfsd restart
  • Add the following to your /etc/nfs.conf:
nfs.server.mount.require_resv_port = 0
nfs.server.verbose = 3
  • Run and put "nfsd" in the search box at the top. sudo nfsd restart and read the messages carefully. Attempt to ddev debug nfsmount the problematic project directory.

Windows-specific NFS debugging

  • Please temporarily disable any firewall or VPN.
  • You can only have one NFS daemon running, so if another application has installed one, you'll want to use that NFS daemon and reconfigure it to allow NFS mounts of your projects.
  1. Stop the running winnfsd service: sudo nssm stop nfsd
  2. Run winnfsd manually in the foreground: winnfsd "C:\\". If it returns to the shell prompt immediately there's likely another nfsd service running.
  3. In another window, in a ddev project directory, ddev debug nfsmount to see if it can mount successfully. (The project need not be started.). ddev debug nfsmount is successful, then everything is probably going to work.
  4. After verifying that ~/.ddev/nfs_exports.txt has a line that includes your project directories, sudo nssm start nfsd and nssm status nfsd. The status command should show SERVICE_RUNNING.
  5. These nssm commands may be useful: nssm help, sudo nssm start nfsd, sudo nssm stop nfsd, nssm status nfsd, sudo nssm edit nfsd (pops up a window that may be hidden), and sudo nssm remove nfsd (also pops up a window, doesn't work predictably if you haven't already stopped the service).
  6. nssm logs failures and what it's doing to the system event log. Run "Event Viewer" and filter events as in the image below: Windows Event Viewer.
  7. Please make sure you have excluded winnfsd from the Windows Defender Firewall, as described in the installation instructions above.
  8. On Windows 10 Pro you can "Turn Windows features on or off" and enable "Services for NFS"-> "Client for NFS". The showmount -e command will then show available exports on the current machine. This can help find out if a conflicting server is running or exactly what the problem with exports may be.

Using Mutagen


The experimental Mutagen asynchronous update feature introduced in v1.18 offers advanced performance experiences for some projects. Unlike the NFS feature, it requires no pre-configuration or installation. You do not need to install mutagen. It can also be significantly faster than NFS and massively faster than plain vanilla Docker.

Mutagen can offer massive webserver performance speedups on macOS and traditional Windows; it's not useful on Linux or Windows WSL2, as it adds complexity but doesn't add significant performance.

Docker bind-mounts (the traditional approach to getting your code into the DDEV web container) can be slow on macOS and Windows, even with NFS. The reason is that every file access has to be checked against the file on the host, and Docker's setup to do this on macOS and Windows offers is not very performant. (On Linux and Linux-like systems, Docker provides native file-access performance.)

Mutagen works by decoupling reads and writes inside the container from reads and writes on the host. If something changes on the host, it gets changed "pretty soon" in the container, and if something changes inside the container it gets updated "pretty soon" on the host. This means that the webserver inside the web container does not have to wait for slow file reads or writes, and gets near-native file speeds. However, it also means that at any given moment, the files on the host may not exactly match the files inside the container, and if files are changed both places, conflicts may result.

Another major advantage of Mutagen over NFS is that it supports filesystem notifications, so file-watchers on both the host and inside the container will be notified when changes occur. This is a great advantage for many development tools, which had to poll for changes in the past, but now will be notified via normal inotify/fsnotify techniques.

If you trouble with the Mutagen feature, please try to recreate it and report via one of the support channels. We really want to make it a robust go-to feature. With your help, it has great potential.

Enabling Mutagen

You do not need to separately install mutagen. It's better if you don't have it installed. DDEV does the installation and upgrades when needed.

To begin using Mutagen, just ddev stop and then ddev config --mutagen-enabled and start the project again. If the mutagen artifacts need to be downloaded, they will be downloaded automatically.

To stop using Mutagen on a project, ddev config --mutagen-enabled=false after stopping it.

You can also enable mutagen globally (for every project) with ddev config global --mutagen-enabled

Note that the nfs-mount-enabled feature is automatically turned off if you're using mutagen.

You can run mutagen on all your projects, there's no limit. To configure it globally, ddev config global --mutagen-enabled.

Caveats about Mutagen Integration

  • Not for every project: Mutagen is not the right choice for every project. If filesystem consistency is your highest priority (as opposed to performance) then you'll want to walk carefully. At this point, there haven't been major issues reported, but two-way sync is a very difficult computational problem, and problems may surface. If you have backups (Time Machine!) and code under source control, you should be fine.
  • Only one mutagen version on machine please: DDEV installs its own mutagen. You do not need to install mutagen. Multiple mutagen versions can't coexist on one machine, so please stop any running mutagen. On macOS, killall mutagen. If you absolutely have to have mutagen installed via homebrew or another technique (for another project) make sure it's the same version as you get with ddev version.
  • Works everywhere, best on macOS: This is mostly for macOS users. WSL2 is already the preferred environment for Windows users, but if you're still using traditional Windows this makes a huge difference. Although DDEV with mutagen is fully supported and tested on traditional Windows and Linux/WSL2, enabling mutagen on Linux/WSL2 may not be your first choice, since it adds some complexity and very little performance.
  • Increased disk usage: Mutagen integration ends up at least doubling the size of your project code disk usage, because the code exists both on your computer and also inside a docker volume. So take care that you have enough overall disk space, and also (on macOS) that you have enough file space set up in Docker Desktop. If you have a large amount of data like user-generated content that does not need syncing (i.e. fileadmin for TYPO3 or sites/default/files for Drupal), you can exclude specific directories from getting synced and use regular docker mount for them instead. See below for Advanced Mutagen configuration options.
  • If your project is likely to change the same file on both the host and inside the container, you may be at risk for conflicts.
  • Massive changes to either the host or the container are the most likely to introduce issues. This integration has been tested extensively with major changes introduced by ddev composer and ddev composer create but be aware of this issue. Changing git branches or a script that deletes huge sections of the synced data are related behaviors that should raise caution.
  • Mutagen is asynchronous: If you make a massive change on either the host or inside the container, you may not see the results for a little while. In studying situations like this, use ddev mutagen monitor to watch what's going on on your computer.
  • No project-level git inside container: The project-level .git directory is not synced by default, because using git at the project level inside the container isn't recommended. But you can change this in the .ddev/mutagen/mutagen.yml.
  • ddev mutagen sync: You can cause an explicit sync with ddev mutagen sync and see syncing status with ddev mutagen status. Note that both ddev start and ddev stop automatically force a mutagen sync.
  • Composer: If you do composer actions inside the container (with ddev ssh) you'll probably want to do a ddev mutagen sync to make sure they get synced as soon as possible, although most people won't ever notice the difference and mutagen will get it synced soon enough.
  • Big git operations (like switching branches) are best done on the host side, rather than inside the container, and you may want to do an explicit ddev mutagen sync command after doing something like that.
  • Project with users who don't want mutagen: If you share a project with some users (perhaps on macOS) that want mutagen and other users (perhaps on WSL2) that don't want or need it, then don't check in the mutagen_enabled: true in the .ddev/config.yaml. Instead, you can either use global mutagen configuration or add a not-checked-in project-level .ddev/config.mutagen.yaml that just has mutagen_enabled: true in it. Then only users that have that will have mutagen enabled.
  • Mutagen restrictions on Windows symlinks: On macOS and Linux (including WSL2) the default .ddev/mutagen/mutagen.yml chooses the posix-raw type of symlink handling (See mutagen docs. This basically means that any symlink created will try to sync, regardless of whether it's valid in the other environment. However, Mutagen does not support posix-raw on traditional Windows, so ddev uses the portable symlink mode. So on Windows with Mutagen... symlinks have to be strictly limited to relative links that are inside the mutagen section of the project.
  • Backups!!!: Keep backups. Mutagen syncing is an experimental feature.

Syncing after git checkout

In general, it's best practice on most projects to do significant git operations on the host, but they can be disruptive to the sync. It's easy to add a git post-checkout hook to do a ddev mutagen sync operation though. Add the file .git/hooks/post-checkout to your project and set it to be executable (chmod +x .git/hooks/post-checkout):

ddev mutagen sync || true

Syncing after yarn actions

Yarn actions can also set off massive filesystem changes. The ddev yarn command mitigates this problem by doing a mutagen sync after taking the action. So you can use ddev yarn install instead of using yarn directly, and it will take care of this for you. Alternately, you can just ddev mutagen sync after doing any similar action that has large filesystem consequences.

Advanced Mutagen configuration options

The Mutagen project provides extensive configuration options that are documented on the site.

Each project by default already has a .ddev/mutagen/mutagen.yml file with basic defaults which you can override if you remove the #ddev-generated line at the beginning of the file.

Remember if you edit the .ddev/mutagen/mutagen.yml file:

  • Remove the #ddev-generated line
  • Execute a ddev mutagen reset to avoid the situation where the docker volume still has files from an older configuration.

The most likely thing you'll want to do is to exclude a path from mutagen syncing, which you can do in the paths: section of the ignore: stanza in the .ddev/mutagen/mutagen.yml.

It is possible to exclude mutagen syncing from a path and then bind-mount something from the host or a different volume on that path with a docker-compose.*.yaml file. So if you have an extremely heavyweight subdirectory in your project (lots of fonts or user-generated content for example), you could exclude that subdirectory in the .ddev/mutagen/mutagen.yml and then add a docker-compose.exclude.yaml.

For example, if you want the .tarballs subdirectory of the project to be available inside the container, but do not need mutagen to be syncing it, you can use normal docker bind-mounting for that subdirectory with this procedure:

  1. Take over the .ddev/mutagen/mutagen.yml by removing the #ddev-generated line

  2. Add /.tarballs to the excluded paths:

            - "/.tarballs"
  3. Add a .ddev/docker-compose.bindmount.yaml something like this:

    version: "3.6"
          - "./.tarballs:/var/www/html/.tarballs" 

Troubleshooting Mutagen Sync Issues

  • Please make sure that DDEV projects work without mutagen before troubleshooting mutagen. ddev config --mutagen-enabled=false && ddev restart.
  • DDEV's mutagen may not be compatible with an existing mutagen on your system. Please make sure that any mutagen installs you have are not running, or stop them. You may want to brew uninstall mutagen-io/mutagen/mutagen mutagen-io/mutagen/mutagen-beta to get rid of brew-installed versions.
  • DDEV's mutagen is installed in ~/.ddev/bin/mutagen. You can use all the features of mutagen by running that, including ~/.ddev/bin/mutagen sync list and ~/.ddev/bin/mutagen daemon stop.
    You can run the script to gather some information about the setup of mutagen. Please report its output when creating an issue or otherwise seeking support.
  • Try ~/.ddev/bin/mutagen daemon stop && ~/.ddev/bin/mutagen daemon start to restart the mutagen daemon if you suspect it's hanging.
  • Use ddev mutagen reset if you suspect trouble (and always after changing the .ddev/mutagen/mutagen.yml. This restarts everything from scratch, including the docker volume that's used to store your project inside the container.)
  • ddev mutagen monitor can help watch mutagen behavior. It's the same as ~/.ddev/bin/mutagen sync monitor <syncname>
  • ddev debug mutagen will let you run any mutagen command using the binary in ~/.ddev/bin/mutagen.
  • If you're working on the host and expecting things to show up immediately inside the container, you can learn a lot by running ddev mutagen monitor in a separate window as you work. You'll see when mutagen responds to your changes and get an idea about how much delay there is.
  • Consider ddev stop before massive file change operations (like moving a directory, etc.)
  • If you get in real trouble, ddev stop, reset your files with git, and then ddev mutagen reset to throw away the docker volume (which may already have incorrect files on it.)
  • If you're having trouble, we really want to hear from you to learn and try to sort it out. See the Support channels.

Mutagen Strategies and Design Considerations

Mutagen provides enormous speed boosts in everyday usage, but of course it's trying desperately under the hood to keep everything that changes in the container updated in the host, and vice versa.

DDEV mounts a fast Docker volume onto /var/www/html inside the web container and then delegates to the mutagen daemon (on the host) the job of keeping all the contents of the project on the host in sync with the contents of the docker volume.

The strategy in the DDEV integration is to try to make sure that at key points everything is completely in sync (consistent). Consistency is a really high priority for this integration.

The life cycle of the mutagen daemon and sync sessions are something like this:

  1. On ddev start the mutagen agent will be started if it's not already running.
  2. If there is already a sync session for this project it's stopped and recreated.
  3. On ddev stop and ddev pause the sync session is flushed (made completely consistent) and then terminated.

In addition, a synchronous flush is performed after any ddev composer command, because composer may cause massive changes to the filesystem inside the container, and those need to be synced before operation continues.

If you need to reset everything for a project, you can do it with ddev mutagen reset which starts the mutagen session from scratch and removes the docker volume so it can be recreated from scratch.

Interaction with other usages of Mutagen

DDEV requires and provides a specific version of Mutagen, which you can see with ddev version.

Mutagen does not guarantee interoperability between different mutagen versions, so you may have trouble if you have another version of mutagen installed. You can find out what version of mutagen you may have installed outside of DDEV with mutagen version.

You'll want your system version of mutagen to be the same as the one provided with DDEV if you're using mutagen for anything else, see the Mutagen installation instructions and install the required version.

Last update: 2021-11-10