Merge branch 'docs-bprescott-202103014-lfsrails' into 'master'

Remove dangling LFS objects from database

See merge request gitlab-org/gitlab!55737

doc/administration/raketasks/check.md

@@ -245,3 +245,9 @@ Upload.find_each do |upload|
 end
 p "#{uploads_deleted} remote objects were destroyed."
 ```
+
+### Delete references to missing LFS objects
+
+If `gitlab-rake gitlab:lfs:check VERBOSE=1` detects LFS objects that exist in the database
+but not on disk, [follow the procedure in the LFS documentation](../../topics/git/lfs/index.md#missing-lfs-objects)
+to remove the database entries.

doc/topics/git/lfs/index.md

@@ -269,3 +269,46 @@ You might choose to do this if you are using an appliance like a <!-- vale gitla
 GitLab can't verify LFS objects. Pushes then fail if you have GitLab LFS support enabled.
 
 To stop push failure, LFS support can be disabled in the [Project settings](../../../user/project/settings/index.md), which also disables GitLab LFS value-adds (Verifying LFS objects, UI integration for LFS).
+
+### Missing LFS objects
+
+An error about a missing LFS object may occur in either of these situations:
+
+- When migrating LFS objects from disk to object storage, with error messages like:
+
+   ```plaintext
+   ERROR -- : Failed to transfer LFS object
+   006622269c61b41bf14a22bbe0e43be3acf86a4a446afb4250c3794ea47541a7
+   with error: No such file or directory @ rb_sysopen -
+   /var/opt/gitlab/gitlab-rails/shared/lfs-objects/00/66/22269c61b41bf14a22bbe0e43be3acf86a4a446afb4250c3794ea47541a7
+   ```
+
+   (Line breaks have been added for legibility.)
+
+- When running the
+  [integrity check for LFS objects](../../../administration/raketasks/check.md#uploaded-files-integrity)
+  with the `VERBOSE=1` parameter.
+
+The database can have records for LFS objects which are not on disk. The database entry may
+[prevent a new copy of the object being pushed](https://gitlab.com/gitlab-org/gitlab-foss/-/issues/49241).
+To delete these references:
+
+1. [Start a rails console](../../../administration/operations/rails_console.md).
+1. Query the object that's reported as missing in the rails console, to return a file path:
+
+   ```ruby
+   lfs_object = LfsObject.find_by(oid: '006622269c61b41bf14a22bbe0e43be3acf86a4a446afb4250c3794ea47541a7')
+   lfs_object.file.path
+   ```
+
+1. Check on disk if it exists:
+
+   ```shell
+   ls -al /var/opt/gitlab/gitlab-rails/shared/lfs-objects/00/66/22269c61b41bf14a22bbe0e43be3acf86a4a446afb4250c3794ea47541a7
+   ```
+
+1. If the file is not present, remove the database record via the rails console:
+
+   ```ruby
+   lfs_object.destroy
+   ```