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+# Moving repositories managed by GitLab
+
+Sometimes you need to move all repositories managed by GitLab to
+another filesystem or another server. In this document we will look
+at some of the ways you can copy all your repositories from
+`/var/opt/gitlab/git-data/repositories` to `/mnt/gitlab/repositories`.
+
+We will look at three scenarios: the target directory is empty, the
+target directory contains an outdated copy of the repositories, and
+how to deal with thousands of repositories.
+
+**Each of the approaches we list can/will overwrite data in the
+target directory `/mnt/gitlab/repositories`. Do not mix up the
+source and the target.**
+
+## Target directory is empty: use a tar pipe
+
+If the target directory `/mnt/gitlab/repositories` is empty the
+simplest thing to do is to use a tar pipe.  This method has low
+overhead and tar is almost always already installed on your system.
+However, it is not possible to resume an interrupted tar pipe:  if
+that happens then all data must be copied again.
+
+```
+# As the git user
+tar -C /var/opt/gitlab/git-data/repositories -cf - -- . |\
+  tar -C /mnt/gitlab/repositories -xf -
+```
+
+If you want to see progress, replace `-xf` with `-xvf`.
+
+### Tar pipe to another server
+
+You can also use a tar pipe to copy data to another server. If your
+'git' user has SSH access to the newserver as 'git@newserver', you
+can pipe the data through SSH.
+
+```
+# As the git user
+tar -C /var/opt/gitlab/git-data/repositories -cf - -- . |\
+  ssh git@newserver tar -C /mnt/gitlab/repositories -xf -
+```
+
+If you want to compress the data before it goes over the network
+(which will cost you CPU cycles) you can replace `ssh` with `ssh -C`.
+
+## The target directory contains an outdated copy of the repositories: use rsync
+
+If the target directory already contains a partial / outdated copy
+of the repositories it may be wasteful to copy all the data again
+with tar. In this scenario it is better to use rsync. This utility
+is either already installed on your system or easily installable
+via apt, yum etc.
+
+```
+# As the 'git' user
+rsync -a --delete /var/opt/gitlab/git-data/repositories/. \
+  /mnt/gitlab/repositories
+```
+
+The `/.` in the command above is very important, without it you can
+easily get the wrong directory structure in the target directory.
+If you want to see progress, replace `-a` with `-av`.
+
+### Single rsync to another server
+
+If the 'git' user on your source system has SSH access to the target
+server you can send the repositories over the network with rsync.
+
+```
+# As the 'git' user
+rsync -a --delete /var/opt/gitlab/git-data/repositories/. \
+  git@newserver:/mnt/gitlab/repositories
+```
+
+## Thousands of Git repositories: use one rsync per repository
+
+Every time you start an rsync job it has to inspect all files in
+the source directory, all files in the target directory, and then
+decide what files to copy or not. If the source or target directory
+has many contents this startup phase of rsync can become a burden
+for your GitLab server. In cases like this you can make rsync's
+life easier by dividing its work in smaller pieces, and sync one
+repository at a time.
+
+In addition to rsync we will use [GNU
+Parallel](http://www.gnu.org/software/parallel/). This utility is
+not included in GitLab so you need to install it yourself with apt
+or yum.  Also note that the GitLab scripts we used below were added
+in GitLab 8.1.
+
+** This process does not clean up repositories at the target location that no
+longer exist at the source. ** If you start using your GitLab instance with
+`/mnt/gitlab/repositories`, you need to run `gitlab-rake gitlab:cleanup:repos`
+after switching to the new repository storage directory.
+
+### Parallel rsync for all repositories known to GitLab
+
+This will sync repositories with 10 rsync processes at a time. We keep
+track of progress so that the transfer can be restarted if necessary.
+
+First we create a new directory, owned by 'git', to hold transfer
+logs. We assume the directory is empty before we start the transfer
+procedure, and that we are the only ones writing files in it.
+
+```
+# Omnibus
+sudo mkdir /var/opt/gitlab/transfer-logs
+sudo chown git:git /var/opt/gitlab/transfer-logs
+
+# Source
+sudo -u git -H mkdir /home/git/transfer-logs
+```
+
+We seed the process with a list of the directories we want to copy.
+
+```
+# Omnibus
+sudo -u git sh -c 'gitlab-rake gitlab:list_repos > /var/opt/gitlab/transfer-logs/all-repos-$(date +%s).txt'
+
+# Source
+cd /home/git/gitlab
+sudo -u git -H sh -c 'bundle exec rake gitlab:list_repos > /home/git/transfer-logs/all-repos-$(date +%s).txt'
+```
+
+Now we can start the transfer. The command below is idempotent, and
+the number of jobs done by GNU Parallel should converge to zero. If it
+does not some repositories listed in all-repos-1234.txt may have been
+deleted/renamed before they could be copied.
+
+```
+# Omnibus
+sudo -u git sh -c '
+cat /var/opt/gitlab/transfer-logs/* | sort | uniq -u |\
+  /usr/bin/env JOBS=10 \
+  /opt/gitlab/embedded/service/gitlab-rails/bin/parallel-rsync-repos \
+    /var/opt/gitlab/transfer-logs/success-$(date +%s).log \
+    /var/opt/gitlab/git-data/repositories \
+    /mnt/gitlab/repositories
+'
+
+# Source
+cd /home/git/gitlab
+sudo -u git -H sh -c '
+cat /home/git/transfer-logs/* | sort | uniq -u |\
+  /usr/bin/env JOBS=10 \
+  bin/parallel-rsync-repos \
+    /home/git/transfer-logs/success-$(date +%s).log \
+    /home/git/repositories \
+    /mnt/gitlab/repositories
+`
+```
+
+### Parallel rsync only for repositories with recent activity
+
+Suppose you have already done one sync that started after 2015-10-1 12:00 UTC.
+Then you might only want to sync repositories that were changed via GitLab
+_after_ that time. You can use the 'SINCE' variable to tell 'rake
+gitlab:list_repos' to only print repositories with recent activity.
+
+```
+# Omnibus
+sudo gitlab-rake gitlab:list_repos SINCE='2015-10-1 12:00 UTC' |\
+  sudo -u git \
+  /usr/bin/env JOBS=10 \
+  /opt/gitlab/embedded/service/gitlab-rails/bin/parallel-rsync-repos \
+    success-$(date +%s).log \
+    /var/opt/gitlab/git-data/repositories \
+    /mnt/gitlab/repositories
+
+# Source
+cd /home/git/gitlab
+sudo -u git -H bundle exec rake gitlab:list_repos SINCE='2015-10-1 12:00 UTC' |\
+  sudo -u git -H \
+  /usr/bin/env JOBS=10 \
+  bin/parallel-rsync-repos \
+    success-$(date +%s).log \
+    /home/git/repositories \
+    /mnt/gitlab/repositories
+```