Transactional File LockingΒΆ
ownCloud’s Transactional File Locking mechanism locks files to avoid file corruption during normal operation. It performs these functions:
- 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
Note
Transactional file locking is in core, and replaces the old File Locking app. The File Locking app has been removed from ownCloud in version 8.2.1. If your ownCloud server still has the File Locking app, you must visit your Apps page to verify that it is disabled; the File Locking app and Transactional File Locking cannot both operate at the same time.
When you see the warning on your ownCloud admin page “Transactional file locking is using the database as locking backend, for best performance it’s advised to configure a memcache for locking”, you are not required to use a memcache. File locking is enabled by default, using the database locking backend. This places a significant load on your database. Using memcache.locking relieves the database load and improves performance. Admins of ownCloud servers with heavy workloads should install a memcache. (See Configuring Memory Caching.)
To use a memcache with Transactional File Locking, you must install the Redis server and corresponding PHP module. 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,
'password' => '', // Optional, if not defined no password will be used.
),
Note
For enhanced security it is recommended to configure Redis to require a password. See http://redis.io/topics/security for more information.
If you want to configure Redis 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,
),
See config.sample.php to see configuration examples for Redis, and for all supported memcaches.
If you are on Ubuntu you can follow this guide for a complete installation from scratch.
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.