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# Transactional File Locking

ownCloud’s new transactional file locking mechanism operates differently than the old File Locking application, and will eventually replace it. The purpose of this mechanism is to avoid file corruption during normal operation. If you select to use the new file locking mechanism make sure you disable the File Locking app.

The new file locking mechanism has these capabilities:

- Operates at a higher level than the filesystem, so you don’t need to use a filesystem that supports locking
- Locks parent directories so they cannot be renamed during any activity on files inside the directories
- Releases locks after file transactions are interrupted, for example when a sync client loses the connection during an upload
- Manages locking and releasing locks correctly on shared files during changes from multiple users
- Manages locks correctly on external storage mounts
- Manages encrypted files correctly

What Transactional File locking is not for: it is not for preventing collisions in collaborative document editing (see Configuring the Collaborative Documents App to learn about collaboration with the Documents app), nor will it prevent multiple users from editing the same document, or give notice that other users are working on the same document. Multiple users can open and edit a file at the same time and Transactional File locking does not prevent this. Rather, it prevents simultaneous file saving.

You must install the Redis server and corresponding PHP module for the new file locking to work. (See Configuring Memory Caching.)

After installing Redis you must enter a configuration in your `config.php` file like this example:

    'filelocking.enabled' => true,
    'memcache.locking' => '\OC\Memcache\Redis',
    'redis' => array(
         'host' => 'localhost',
         'port' => 6379,
         'timeout' => 0.0,
          ),

If you want to connect to Redis configured to listen on an unix socket (which is recommended if Redis is running on the same system as ownCloud) use this example `config.php` configuration:

    'filelocking.enabled' => true,
    'memcache.locking' => '\OC\Memcache\Redis',
    'redis' => array(
         'host' => '/var/run/redis/redis.sock',
         'port' => 0,
         'timeout' => 0.0,
          ),

The Server status section on your ownCloud Admin page indicates whether transactional file locking is enabled or disabled.

See `config.sample.php` to see configuration examples for Redis, and for all supported memcaches.

Learn more about Reds at Redis. Memcached, the popular distributed memory caching system, is not suitable for the new file locking because it is not designed to store locks, and data can disappear from the cache at any time. Redis is a key-value store, and it guarantees that cached objects are available for as long as they are needed.

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