NFS

You can view information and options set for each of the mounted NFS file systems by running sudo nfsstat -m.

NFS Server features

Required features

File locking: GitLab requires advisory file locking, which is only supported natively in NFS version 4. NFSv3 also supports locking as long as Linux Kernel 2.6.5+ is used. We recommend using version 4 and do not specifically test NFSv3.

Recommended options

When you define your NFS exports, we recommend you also add the following options:

no_root_squash - NFS normally changes the root user to nobody. This is a good security measure when NFS shares will be accessed by many different users. However, in this case only GitLab will use the NFS share so it is safe. GitLab recommends the no_root_squash setting because we need to manage file permissions automatically. Without the setting you may receive errors when the Omnibus package tries to alter permissions. Note that GitLab and other bundled components do not run as root but as non-privileged users. The recommendation for no_root_squash is to allow the Omnibus package to set ownership and permissions on files, as needed.
sync - Force synchronous behavior. Default is asynchronous and under certain circumstances it could lead to data loss if a failure occurs before data has synced.

AWS Elastic File System

GitLab strongly recommends against using AWS Elastic File System (EFS). Our support team will not be able to assist on performance issues related to file system access.

Customers and users have reported that AWS EFS does not perform well for GitLab's use-case. There are several issues that can cause problems. For these reasons GitLab does not recommend using EFS with GitLab.

EFS bases allowed IOPS on volume size. The larger the volume, the more IOPS are allocated. For smaller volumes, users may experience decent performance for a period of time due to 'Burst Credits'. Over a period of weeks to months credits may run out and performance will bottom out.
To keep "Burst Credits" available, it may be necessary to provision more space with 'dummy data'. However, this may get expensive.
Another option to maintain "Burst Credits" is to use FS Cache on the server so that AWS doesn't always have to go into EFS to access files.
For larger volumes, allocated IOPS may not be the problem. Workloads where many small files are written in a serialized manner are not well-suited for EFS. EBS with an NFS server on top will perform much better.

In addition, avoid storing GitLab log files (e.g. those in /var/log/gitlab) because this will also affect performance. We recommend that the log files be stored on a local volume.

For more details on another person's experience with EFS, see Amazon's Elastic File System: Burst Credits

NFS Client mount options

Below is an example of an NFS mount point defined in /etc/fstab we use on GitLab.com:

10.1.1.1:/var/opt/gitlab/git-data /var/opt/gitlab/git-data nfs4 defaults,soft,rsize=1048576,wsize=1048576,noatime,nobootwait,lookupcache=positive 0 2

Notice several options that you should consider using:

Setting	Description
`nobootwait`	Don't halt boot process waiting for this mount to become available
`lookupcache=positive`	Tells the NFS client to honor `positive` cache results but invalidates any `negative` cache results. Negative cache results cause problems with Git. Specifically, a `git push` can fail to register uniformly across all NFS clients. The negative cache causes the clients to 'remember' that the files did not exist previously.

Mount locations

When using default Omnibus configuration you will need to share 5 data locations between all GitLab cluster nodes. No other locations should be shared. The following are the 5 locations you need to mount:

Location	Description	Default configuration
`/var/opt/gitlab/git-data`	Git repository data. This will account for a large portion of your data	`git_data_dirs({"default" => "/var/opt/gitlab/git-data"})`
`/var/opt/gitlab/.ssh`	SSH `authorized_keys` file and keys used to import repositories from some other Git services	`user['home'] = '/var/opt/gitlab/'`
`/var/opt/gitlab/gitlab-rails/uploads`	User uploaded attachments	`gitlab_rails['uploads_directory'] = '/var/opt/gitlab/gitlab-rails/uploads'`
`/var/opt/gitlab/gitlab-rails/shared`	Build artifacts, GitLab Pages, LFS objects, temp files, etc. If you're using LFS this may also account for a large portion of your data	`gitlab_rails['shared_path'] = '/var/opt/gitlab/gitlab-rails/shared'`
`/var/opt/gitlab/gitlab-ci/builds`	GitLab CI build traces	`gitlab_ci['builds_directory'] = '/var/opt/gitlab/gitlab-ci/builds'`

Other GitLab directories should not be shared between nodes. They contain node-specific files and GitLab code that does not need to be shared. To ship logs to a central location consider using remote syslog. GitLab Omnibus packages provide configuration for UDP log shipping.

Consolidating mount points

If you don't want to configure 5-6 different NFS mount points, you have a few alternative options.

Change default file locations

Omnibus allows you to configure the file locations. With custom configuration you can specify just one main mountpoint and have all of these locations as subdirectories. Mount /gitlab-data then use the following Omnibus configuration to move each data location to a subdirectory:

git_data_dirs({"default" => "/gitlab-data/git-data"})
user['home'] = '/gitlab-data/home'
gitlab_rails['uploads_directory'] = '/gitlab-data/uploads'
gitlab_rails['shared_path'] = '/gitlab-data/shared'
gitlab_ci['builds_directory'] = '/gitlab-data/builds'

To move the git home directory, all GitLab services must be stopped. Run gitlab-ctl stop && initctl stop gitlab-runsvdir. Then continue with the reconfigure.

Run sudo gitlab-ctl reconfigure to start using the central location. Please be aware that if you had existing data you will need to manually copy/rsync it to these new locations and then restart GitLab.

Bind mounts

Bind mounts provide a way to specify just one NFS mount and then bind the default GitLab data locations to the NFS mount. Start by defining your single NFS mount point as you normally would in /etc/fstab. Let's assume your NFS mount point is /gitlab-data. Then, add the following bind mounts in /etc/fstab:

/gitlab-data/git-data /var/opt/gitlab/git-data none bind 0 0
/gitlab-data/.ssh /var/opt/gitlab/.ssh none bind 0 0
/gitlab-data/uploads /var/opt/gitlab/gitlab-rails/uploads none bind 0 0
/gitlab-data/shared /var/opt/gitlab/gitlab-rails/shared none bind 0 0
/gitlab-data/builds /var/opt/gitlab/gitlab-ci/builds none bind 0 0

Read more on high-availability configuration:

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NFS