Binlogs, or binary log files, are logs of all MySQL INSERT, UPDATE, and DELETE queries executed against your subscription’s active database. By replaying the queries in binlogs against your passive database, MySQL keeps your passive database synchronized with changes made to your active database. Queries that read only from your MySQL database without changing the contents, such as SELECT queries, are not tracked in binlogs.

Non-production environments also maintain binlogs, despite the lack of database redundancy, to preserve feature and performance parity between production and non-production environments.

Binlogs are not available to download from the Cloud Platform interface and are not available to subscribers.

Binlogs and website performance

If websites create too many binlogs too rapidly, those binlogs can fill your database partition and cause downtime. Some common causes of rapid binlog creation are as follows:

• A large database import.
• A large quantity of cache-related queries (due to queries that write Drupal cache data to the database can contain megabytes of serialized data. To reduce or eliminate these UPDATE queries to your database, install and configure memcached).
• Web crawlers requesting several uncached pages in quick succession.
• INSERT queries from Drupal’s database logging module (Acquia recommends that you disable this module, and use the Syslog module instead).

If MySQL can no longer write to binlogs, Cloud Platform cannot process changes to your database or replicate those changes to your secondary database, which can cause MySQL to stop responding. In specific cases, however, read-only queries of the database may continue to function properly.

Acquia monitors disk utilization and notifies customers when binlogs are filling disk volumes too rapidly. For more information about examining your disk storage usage, see About disk storage in Cloud Platform.

Binlog management

Cloud Platform rotates and compresses binlogs when they become 1.1 GB in size. If binlogs are not needed after 6 hours, they are deleted.

In emergency situations, Acquia can remove binlogs less than six hours old to help prevent website downtime.

Binlogs