Does svnadmin hotcopy lock the source repository during the copy operation?

Answer to the core question

Running svnadmin hotcopy **does acquire a lock on the source repository** that blocks write operations (commits) until the copy completes. Read‑only operations such as svn update continue normally.

What the lock looks like

The lock is a file named db/lock in the repository’s root directory. When the file exists, any process attempting to perform a write operation will either block or return a lock error until the file is removed.

Hook scripts are copied verbatim

The hooks directory is part of the repository tree, so svnadmin hotcopy copies it exactly. On POSIX systems executable bits are preserved, meaning the scripts will run on the destination repository without modification. Windows copies may lose executable permissions; verify by running chmod +x on the scripts if needed.

Using svn switch --relocate while the original repo remains online

Clients can relocate their working copies to the new URL at any time. As long as the original repository stays reachable, svn switch --relocate performs a simple URL rewrite and does not interfere with ongoing commits or updates.

Practical steps for a zero‑downtime move

1. Verify the repository is in a consistent state (e.g., run svnadmin verify /path/to/repo).

2. Start the hotcopy on a low‑traffic window:

   svnadmin hotcopy /srv/svn/oldrepo /srv/svn/backup/newrepo
   

3. While the command runs, any svn commit to the original repo will block or fail with a lock error. Clients can still svn update without interruption.

4. After the hotcopy finishes, confirm the lock file is removed:

   ls -l /srv/svn/oldrepo/db/lock
   # should not exist
   

5. Test the destination repository’s hooks by performing a dummy commit from a fresh working copy:

   svn checkout file:///srv/svn/backup/newrepo wc
   cd wc
   # modify a file
   svn commit -m "Test hook"
   

6. Relocate existing working copies to the new URL:

   svn switch --relocate http://old-host/svn/oldrepo http://new-host/svn/newrepo wc
   

7. Continue normal operations; the original repository will accept commits again once the hotcopy is complete.

Key take‑aways

• Hotcopy locks the source for writes only.
• All hooks are preserved; verify executability on Windows.
• Working copies can be relocated at any time without affecting ongoing commits.

What to verify after the migration

• Check that hooks/pre-commit runs and returns a non‑zero exit code when expected.
• Ensure that absolute paths or environment variables used by hooks are updated to the new host.
• Run a quick commit from a client pointing to the new URL to confirm the repository is fully operational.