Create a users file (i.e. users.txt) for mapping SVN users to Git:
user1 = First Last Name <email@address.com>
user2 = First Last Name <email@address.com>
...
You can use this one-liner to build a template from your existing SVN repository:
svn log -q | awk -F '|' '/^r/ {gsub(/ /, "", $2); sub(" $", "", $2); print $2" = "$2" <"$2">"}' | sort -u > users.txt
SVN will stop if it finds a missing SVN user, not in the file. But after that, you can update the file and pick up where you left off.
Now pull the SVN data from the repository:
git svn clone --stdlayout --no-metadata --authors-file=users.txt svn://hostname/path dest_dir-tmp
This command will create a new Git repository in dest_dir-tmp and start pulling the SVN repository. Note that the "--stdlayout" flag implies you have the common "trunk/, branches/, tags/" SVN layout. If your layout differs, become familiar with --tags, --branches, --trunk options (in general git svn help).
All common protocols are allowed: svn://, http://, https://. The URL should target the base repository, something like http://svn.mycompany.com/myrepo/repository. The URL string must not include /trunk, /tag or /branches.
Note that after executing this command it very often looks like the operation is "hanging/frozen", and it's quite normal that it can be stuck for a long time after initializing the new repository. Eventually, you will then see log messages which indicate that it's migrating.
Also note that if you omit the --no-metadata flag, Git will append information about the corresponding SVN revision to the commit message (i.e. git-svn-id: svn://svn.mycompany.com/myrepo/<branchname/trunk>@<RevisionNumber> <Repository UUID>)
If a user name is not found, update your users.txt file then:
cd dest_dir-tmp
git svn fetch
You might have to repeat that last command several times, if you have a large project until all of the Subversion commits have been fetched:
git svn fetch
When completed, Git will checkout the SVN trunk into a new branch. Any other branches are set up as remotes. You can view the other SVN branches with:
git branch -r
If you want to keep other remote branches in your repository, you want to create a local branch for each one manually. (Skip trunk/master.) If you don't do this, the branches won't get cloned in the final step.
git checkout -b local_branch remote_branch
# It's OK if local_branch and remote_branch are the same names
Tags are imported as branches. You have to create a local branch, make a tag and delete the branch to have them as tags in Git. To do it with tag "v1":
git checkout -b tag_v1 remotes/tags/v1
git checkout master
git tag v1 tag_v1
git branch -D tag_v1
Clone your GIT-SVN repository into a clean Git repository:
git clone dest_dir-tmp dest_dir
rm -rf dest_dir-tmp
cd dest_dir
The local branches that you created earlier from remote branches will only have been copied as remote branches into the newly cloned repository. (Skip trunk/master.) For each branch you want to keep:
git checkout -b local_branch origin/remote_branch
Finally, remove the remote from your clean Git repository that points to the now-deleted temporary repository:
git remote rm origin
Best Answer
I've been working with Magento + SVN(not WebDAV however) myself and didn't have those kind of problems so far. It takes long(as in 2 min) to commit changes to the repository but by no means more than 5 min.
I don't really know the cause of your problem, I just more or less wanted to say that it's usually not like that(or that it might be WebDAV's fault).
Workaround 1:
Assuming that you won't be making changes to the core of Magento, have you considered only versioning those parts of your Magento installation that will be changed by you? i.e. the app/code/local folder where your modules will reside and maybe your template folder. This would drastically reduce the total number of versioned files/folders and thereby significantly increase the synchonizing speed.
Workaround 2:
Always commit only the downmost folder that contains all the updates.
Workaround 3:
Similar to number 1: Try to add everything that doesn't need to be stored in the repo to the ignore list. Things like the var/ folder don't need to be versioned and contain a lot of files, so it might be a good idea not to include them to your repository.
Workaround 4:
Use git instead of SVN if that is an option for you.
eZ Components had the same problems with SVN + WebDAV and someone compared the checkout times between SVN+DAV with git. The results can be seen here.
After seeing those numbers, I think switching is your best available option in the long run.