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diff --git a/doc/administration/high_availability/nfs.md b/doc/administration/high_availability/nfs.md index 6e8dc2c6c57..e3342fa0813 100644 --- a/doc/administration/high_availability/nfs.md +++ b/doc/administration/high_availability/nfs.md @@ -1,322 +1,5 @@ --- -type: reference +redirect_to: ../nfs.md --- -# NFS - -You can view information and options set for each of the mounted NFS file -systems by running `nfsstat -m` and `cat /etc/fstab`. - -CAUTION: **Caution:** -From GitLab 13.0, using NFS for Git repositories is deprecated. In GitLab 14.0, -support for NFS for Git repositories is scheduled to be removed. Upgrade to -[Gitaly Cluster](../gitaly/praefect.md) as soon as possible. - -NOTE: **Note:** -Filesystem performance has a big impact on overall GitLab -performance, especially for actions that read or write to Git repositories. See -[Filesystem Performance Benchmarking](../operations/filesystem_benchmarking.md) -for steps to test filesystem performance. - -## Known kernel version incompatibilities - -RedHat Enterprise Linux (RHEL) and CentOS v7.7 and v7.8 ship with kernel -version `3.10.0-1127`, which [contains a -bug](https://bugzilla.redhat.com/show_bug.cgi?id=1783554) that causes -[uploads to fail to copy over NFS](https://gitlab.com/gitlab-org/gitlab/-/issues/218999). The -following GitLab versions include a fix to work properly with that -kernel version: - -1. [12.10.12](https://about.gitlab.com/releases/2020/06/25/gitlab-12-10-12-released/) -1. [13.0.7](https://about.gitlab.com/releases/2020/06/25/gitlab-13-0-7-released/) -1. [13.1.1](https://about.gitlab.com/releases/2020/06/24/gitlab-13-1-1-released/) -1. 13.2 and up - -If you are using that kernel version, be sure to upgrade GitLab to avoid -errors. - -## 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. In some cases where the - `no_root_squash` option is not available, the `root` flag can achieve the same - result. -- `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. - -Due to the complexities of running Omnibus with LDAP and the complexities of -maintaining ID mapping without LDAP, in most cases you should enable numeric UIDs -and GIDs (which is off by default in some cases) for simplified permission -management between systems: - -- [NetApp instructions](https://library.netapp.com/ecmdocs/ECMP1401220/html/GUID-24367A9F-E17B-4725-ADC1-02D86F56F78E.html) -- For non-NetApp devices, disable NFSv4 `idmapping` by performing opposite of [enable NFSv4 idmapper](https://wiki.archlinux.org/index.php/NFS#Enabling_NFSv4_idmapping) - -### Disable NFS server delegation - -We recommend that all NFS users disable the NFS server delegation feature. This -is to avoid a [Linux kernel bug](https://bugzilla.redhat.com/show_bug.cgi?id=1552203) -which causes NFS clients to slow precipitously due to -[excessive network traffic from numerous `TEST_STATEID` NFS messages](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/52017). - -To disable NFS server delegation, do the following: - -1. On the NFS server, run: - - ```shell - echo 0 > /proc/sys/fs/leases-enable - sysctl -w fs.leases-enable=0 - ``` - -1. Restart the NFS server process. For example, on CentOS run `service nfs restart`. - -#### Important notes - -The kernel bug may be fixed in -[more recent kernels with this commit](https://github.com/torvalds/linux/commit/95da1b3a5aded124dd1bda1e3cdb876184813140). - -Red Hat Enterprise 7 [shipped a kernel update](https://access.redhat.com/errata/RHSA-2019:2029) -on August 6, 2019 that may also have resolved this problem. - -You may not need to disable NFS server delegation if you know you are using a version of -the Linux kernel that has been fixed. That said, GitLab still encourages instance -administrators to keep NFS server delegation disabled. - -### Improving NFS performance with GitLab - -#### Improving NFS performance with Unicorn - -NOTE: **Note:** -From GitLab 12.1, it will automatically be detected if Rugged can and should be used per storage. - -If you previously enabled Rugged using the feature flag, you will need to unset the feature flag by using: - -```shell -sudo gitlab-rake gitlab:features:unset_rugged -``` - -If the Rugged feature flag is explicitly set to either true or false, GitLab will use the value explicitly set. - -#### Improving NFS performance with Puma - -NOTE: **Note:** -From GitLab 12.7, Rugged auto-detection is disabled if Puma thread count is greater than 1. - -If you want to use Rugged with Puma, it is recommended to [set Puma thread count to 1](https://docs.gitlab.com/omnibus/settings/puma.html#puma-settings). - -If you want to use Rugged with Puma thread count more than 1, Rugged can be enabled using the [feature flag](../../development/gitaly.md#legacy-rugged-code) - -If the Rugged feature flag is explicitly set to either true or false, GitLab will use the value explicitly set. - -### Known issues - -#### Avoid using AWS's Elastic File System (EFS) - -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. Workloads where many small files are written in a serialized manner, like `git`, -are not well-suited for EFS. EBS with an NFS server on top will perform much better. - -If you do choose to use EFS, avoid storing GitLab log files (e.g. those in `/var/log/gitlab`) -there 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 this [Commit Brooklyn 2019 video](https://youtu.be/K6OS8WodRBQ?t=313). - -#### Avoid using CephFS and GlusterFS - -GitLab strongly recommends against using CephFS and GlusterFS. -These distributed file systems are not well-suited for GitLab's input/output access patterns because Git uses many small files and access times and file locking times to propagate will make Git activity very slow. - -#### Avoid using PostgreSQL with NFS - -GitLab strongly recommends against running your PostgreSQL database -across NFS. The GitLab support team will not be able to assist on performance issues related to -this configuration. - -Additionally, this configuration is specifically warned against in the -[PostgreSQL Documentation](https://www.postgresql.org/docs/current/creating-cluster.html#CREATING-CLUSTER-NFS): - ->PostgreSQL does nothing special for NFS file systems, meaning it assumes NFS behaves exactly like ->locally-connected drives. If the client or server NFS implementation does not provide standard file ->system semantics, this can cause reliability problems. Specifically, delayed (asynchronous) writes ->to the NFS server can cause data corruption problems. - -For supported database architecture, please see our documentation on -[Configuring a Database for GitLab HA](../postgresql/replication_and_failover.md). - -## NFS Client mount options - -Here is an example snippet to add to `/etc/fstab`: - - ```plaintext - 10.1.0.1:/var/opt/gitlab/.ssh /var/opt/gitlab/.ssh nfs4 defaults,vers=4.1,hard,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2 - 10.1.0.1:/var/opt/gitlab/gitlab-rails/uploads /var/opt/gitlab/gitlab-rails/uploads nfs4 defaults,vers=4.1,hard,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2 - 10.1.0.1:/var/opt/gitlab/gitlab-rails/shared /var/opt/gitlab/gitlab-rails/shared nfs4 defaults,vers=4.1,hard,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2 - 10.1.0.1:/var/opt/gitlab/gitlab-ci/builds /var/opt/gitlab/gitlab-ci/builds nfs4 defaults,vers=4.1,hard,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2 - 10.1.0.1:/var/opt/gitlab/git-data /var/opt/gitlab/git-data nfs4 defaults,vers=4.1,hard,rsize=1048576,wsize=1048576,noatime,nofail,lookupcache=positive 0 2 - ``` - -Note there are several options that you should consider using: - -| Setting | Description | -| ------- | ----------- | -| `vers=4.1` |NFS v4.1 should be used instead of v4.0 because there is a Linux [NFS client bug in v4.0](https://gitlab.com/gitlab-org/gitaly/-/issues/1339) that can cause significant problems due to stale data. -| `nofail` | 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. -| `hard` | Instead of `soft`. [Further details](#soft-mount-option). - -### soft mount option - -We recommend that you use `hard` in your mount options, unless you have a specific -reason to use `soft`. - -On GitLab.com, we use `soft` because there were times when we had NFS servers -reboot and `soft` improved availability, but everyone's infrastructure is different. -If your NFS is provided by on-premise storage arrays with redundant controllers, -for example, you shouldn't need to worry about NFS server availability. - -The NFS man page states: - -> "soft" timeout can cause silent data corruption in certain cases - -Read the [Linux man page](https://linux.die.net/man/5/nfs) to understand the difference, -and if you do use `soft`, ensure that you've taken steps to mitigate the risks. - -If you experience behavior that might have been caused by -writes to disk on the NFS server not occurring, such as commits going missing, -use the `hard` option, because (from the man page): - -> use the soft option only when client responsiveness is more important than data integrity - -Other vendors make similar recommendations, including -[SAP](http://wiki.scn.sap.com/wiki/x/PARnFQ) and NetApp's -[knowledge base](https://kb.netapp.com/Advice_and_Troubleshooting/Data_Storage_Software/ONTAP_OS/What_are_the_differences_between_hard_mount_and_soft_mount), -they highlight that if the NFS client driver caches data, `soft` means there is no certainty if -writes by GitLab are actually on disk. - -Mount points set with the option `hard` may not perform as well, and if the -NFS server goes down, `hard` will cause processes to hang when interacting with -the mount point. Use `SIGKILL` (`kill -9`) to deal with hung processes. -The `intr` option -[stopped working in the 2.6 kernel](https://access.redhat.com/solutions/157873). - -## A single NFS mount - -It's recommended to nest all GitLab data directories within a mount, that allows automatic -restore of backups without manually moving existing data. - -```plaintext -mountpoint -└── gitlab-data - ├── builds - ├── git-data - ├── shared - └── uploads -``` - -To do so, we'll need to configure Omnibus with the paths to each directory nested -in the mount point as follows: - -Mount `/gitlab-nfs` then use the following Omnibus -configuration to move each data location to a subdirectory: - -```ruby -git_data_dirs({"default" => { "path" => "/gitlab-nfs/gitlab-data/git-data"} }) -gitlab_rails['uploads_directory'] = '/gitlab-nfs/gitlab-data/uploads' -gitlab_rails['shared_path'] = '/gitlab-nfs/gitlab-data/shared' -gitlab_ci['builds_directory'] = '/gitlab-nfs/gitlab-data/builds' -``` - -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 - -Alternatively to changing the configuration in Omnibus, bind mounts can be used -to store the data on an NFS mount. - -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-nfs`. Then, add the following bind mounts in -`/etc/fstab`: - -```shell -/gitlab-nfs/gitlab-data/git-data /var/opt/gitlab/git-data none bind 0 0 -/gitlab-nfs/gitlab-data/.ssh /var/opt/gitlab/.ssh none bind 0 0 -/gitlab-nfs/gitlab-data/uploads /var/opt/gitlab/gitlab-rails/uploads none bind 0 0 -/gitlab-nfs/gitlab-data/shared /var/opt/gitlab/gitlab-rails/shared none bind 0 0 -/gitlab-nfs/gitlab-data/builds /var/opt/gitlab/gitlab-ci/builds none bind 0 0 -``` - -Using bind mounts will require manually making sure the data directories -are empty before attempting a restore. Read more about the -[restore prerequisites](../../raketasks/backup_restore.md). - -## Multiple NFS mounts - -When using default Omnibus configuration you will need to share 4 data locations -between all GitLab cluster nodes. No other locations should be shared. The -following are the 4 locations need to be shared: - -| 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" => { "path" => "/var/opt/gitlab/git-data"} })` -| `/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/CD 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. Omnibus GitLab packages -provide configuration for [UDP log shipping](https://docs.gitlab.com/omnibus/settings/logs.html#udp-log-shipping-gitlab-enterprise-edition-only). - -Having multiple NFS mounts will require manually making sure the data directories -are empty before attempting a restore. Read more about the -[restore prerequisites](../../raketasks/backup_restore.md). - ---- - -Read more on high-availability configuration: - -1. [Configure the database](../postgresql/replication_and_failover.md) -1. [Configure Redis](redis.md) -1. [Configure the GitLab application servers](gitlab.md) -1. [Configure the load balancers](load_balancer.md) - -<!-- ## Troubleshooting - -Include any troubleshooting steps that you can foresee. If you know beforehand what issues -one might have when setting this up, or when something is changed, or on upgrading, it's -important to describe those, too. Think of things that may go wrong and include them here. -This is important to minimize requests for support, and to avoid doc comments with -questions that you know someone might ask. - -Each scenario can be a third-level heading, e.g. `### Getting error message X`. -If you have none to add when creating a doc, leave this section in place -but commented out to help encourage others to add to it in the future. --> +This document was moved to [another location](../nfs.md). |