XIOS Migration Experiments

XIOS is an XML configured Input Output Server implementation for scientific computing file I/O interactions

This is an attempt to mirror the code base within Git, keeping the subversion history

Local & MyMirror to manage SVN Synchronisation

To set this up, then my Local is configured to use git svn and to communicate with the IPSL code management.

Initial Creation

Create a Local git repository and link this to the IPSL subversion.

git init XIOS-repository-migration-experiments

cd XIOS-repository-migration-experiments

git svn init -s --prefix=ipsl/ --ignore-paths="(test_client\.exe|xios_server\.exe|xios_server1\.exe|xios_server2\.exe)" https://forge.ipsl.fr/ioserver/svn/XIOS3/

git svn fetch

(Notes:

• --ignore-paths is essential, as
  • there are removed build artefacts in the subversion history which are large
  • and cause problems with the repository history, github uploads, etc.
• git svn fetch MUST complete first time, do not restart after failure!
  • this takes ages; sorry
  • if it fails, delete and start over, do not restart
  • ~/.subversion/servers can be configured, for example extending timeout in global: http-timeout = {}
  • once this has succeeded once, future git svn fetch should only try to update, and be fast )

Note: at this stage, it is worth cross-checking that your Local IPSL branch history matches commit SHAs with the Mirror svn-* branches (if in doubt, ask)

Working with Branches

Subversion synchronisation involves working in a Local git repository.

Updates from IPSL Subversion are obtained, then any Mirror branches that are being managed are rebased using the svn content.

git svn fetch
git checkout svn-trunk
git rebase ipsl/trunk

git checkout main
git rebase ipsl/trunk

The rebase procedure inserts the commits from Subversion in a continuous stream, then applies any branch commits at the top (such as CI testing changes)

This ensures that the subversion change stream is maintain in sync, and any Mirror changes are only applied as addendums to the managed and synchronised code.