Add new "Troubleshooting Git" page to General documentation (Admin).

doc/topics/git/index.md

@@ -61,6 +61,10 @@ We've gathered some resources to help you to get the best from Git with GitLab.
   - [Getting Started with Git LFS](https://about.gitlab.com/2017/01/30/getting-started-with-git-lfs-tutorial/)
   - [Towards a production quality open source Git LFS server](https://about.gitlab.com/2015/08/13/towards-a-production-quality-open-source-git-lfs-server/)
 
+## Troubleshooting
+
+- Learn a few [Git troubleshooting](troubleshooting_git.md) techniques to help you out.
+
 ## General information
 
 - **Articles:**

doc/topics/git/troubleshooting_git.md

+# Troubleshooting Git
+
+Sometimes things don't work the way they should or as you might expect when
+you're using Git. Here are some tips on troubleshooting and resolving issues 
+with Git.
+
+## Error Messages
+
+### ‘Broken pipe’ Errors on Git Push
+
+‘Broken pipe’ errors can occur when attempting to push to a remote repository:
+
+```
+Write failed: Broken pipe
+fatal: The remote end hung up unexpectedly
+```
+
+#### If pushing over HTTP
+
+Try increasing the POST buffer size in Git configuration:
+
+```sh
+git config http.postBuffer 52428800
+```
+
+The value is specified in bytes, so in the above case the buffer size has been 
+set to 50MB. The default is 1MB.
+
+#### If pushing over SSH
+
+1. Check SSH configuration:
+
+	‘Broken pipe’ errors can sometimes be caused by underlying issues with SSH 
+	(such as authentication), so first check that SSH is correctly configured by
+	following the instructions in [SSH Troubleshooting][SSH-Troubleshooting].
+
+1. Prevent session timeouts by configuring SSH ‘keep alive’ either on the client
+	or on the server:
+	
+	>**Note:** configuring *both* the client and the server is unnecessary.
+
+	#### Configure SSH on the client
+	
+	**On Linux (ssh)**
+	
+	Edit `~/.ssh/config` (create the file if it doesn’t exist) and insert:
+	
+	```apache
+	Host your-gitlab-instance-url.com
+	  ServerAliveInterval 60 
+	  ServerAliveCountMax 5	
+	```
+
+	**On Windows (PuTTY)**
+
+	In your session properties, go to *Connection* and under 
+	`Sending of null packets to keep session active`, set 
+	`Seconds between keepalives (0 to turn off)` to 60.
+
+	#### Configure SSH on the server
+
+	Edit `/etc/ssh/sshd_config` and insert:
+	
+	```apache
+	ClientAliveInterval 60
+	ClientAliveCountMax 5	
+	```
+
+#### If 'pack-objects' type errors are also being displayed
+
+1. Try to run a `git repack` before attempting to push to the remote repository again:
+
+	```
+	git repack
+	git push 
+	```
+
+1. If you’re running an older version of Git (< 2.9), consider upgrading Git to >= 2.9 
+(see ‘[Broken pipe when pushing to Git repository][Broken-Pipe]').
+
+[SSH-Troubleshooting]: https://docs.gitlab.com/ce/ssh/README.html#troubleshooting "SSH Troubleshooting"
+
+[Broken-Pipe]: https://stackoverflow.com/questions/19120120/broken-pipe-when-pushing-to-git-repository/36971469#36971469 "StackOverflow: 'Broken pipe when pushing to Git repository'"