Adding external CVMFS repo docs

docs/services/adding-external-cvmfs-repos.md

@@ -0,0 +1,53 @@
+Adding External CVMFS Repos
+===========================
+
+This document describes how to add an external repo like public-uc.osgstorage.org or ligo.storage.igwn.org.
+
+## Use OSG Docs
+Authoritative source for adding new oasis repo is [Install an OASIS Repository](https://osg-htc.org/docs/data/external-oasis-repos/).  Follow instructions starting at heading "Creating a Repository", your first command should be `cvmfs_server mkfs`
+
+When it asks you to open a ticket, if it's an osgstorage.org or opensciencegrid.org domain, then all you need to do is add the CVMFS repo to topology like: https://github.com/opensciencegrid/topology/pull/3986 
+
+Once you have completed adding the fetch-cvmfs-whitelist line to cron, you are done with the OSG documentation.
+
+## Configure the external CVMFS repo
+
+In `/etc/cvmfs/repositories.d/<reponame>/server.conf`, add the lines:
+```
+CVMFS_COMPRESSION_ALGORITHM=none
+CVMFS_GARBAGE_COLLECTION=true
+CVMFS_AUTO_GC=true
+CVMFS_AUTO_GC_TIMESPAN="2 days ago"
+CVMFS_EXTERNAL_DATA=true
+CVMFS_AUTO_TAG_TIMESPAN="2 weeks ago"
+```
+Check in the file for duplicate lines of the above with different settings, comment (`#`) out those lines.
+
+The imporatant line is `CVMFS_COMPRESSION_ALGORITHM`.  If it is set to the default, then CVMFS clients will expect the data to be delivered in compressed format, while the caches will deliver the file in un-compressed format.
+
+## Configure CVMFS-sync
+
+`cvmfs-sync` synchonizes the data from an XRootD server (origin) to a CVMFS repo.
+
+Create a new config file (by copying another existing config) in `/etc/cvmfs-sync`.  The name of the configuration should be `<reponame>.config`
+
+In the config, you will need to modify the repo, source and destination.  This is where cvmfs-sync will scan for new files to add to the CVMFS repo.
+
+### Make the systemd timer
+Copy an existing timer like:
+```
+cp -r /etc/systemd/system/[email protected] /etc/systemd/system/cvmfs-data-update@<reponame>.service.d
+```
+You may need to edit the override file in the directory above to change the user.
+
+Enable the timer:
+```
+systemctl enable cvmfs-data-update@<reponame>.timer
+systemctl start cvmfs-data-update@<reponame>.timer
+```
+
+## Checking cvmfs-sync
+```
+journalctl -u cvmfs-data-update@<reponame>
+```
+

mkdocs.yml

@@ -23,6 +23,7 @@ nav:
   - CE Monitoring Dashboards: 'services/ce-monitoring-dashboards.md'
   - Yum Repository:
     - Troubleshooting Guide for Yum Repository Scripts: 'troubleshooting/repository-scripts.md'
+  - Adding External CVMFS repos: 'services/adding-external-cvmfs-repos.md'
 - Service Level Agreements:
   - General: 'SLA/general.md'
   - Access Point: 'SLA/access-point.md'