This section is an overview of how automatic backups are implemented in a Calendar Server system.
This section covers the following topics:
The Calendar Server system records each transaction for the calendar database (additions, modifications or deletions to calendars and their properties) in a transaction log file. At some predetermined interval, the log file is closed for writing and another is created. The system then applies the transactions from the oldest closed transaction log to the live calendar databases as time permits. When all the transactions in the log have been applied to the database, the log is marked as “already applied”.
When hot backups are configured, a snapshot of the live databases is taken every 24 hours. The already applied logs are then applied to the hot backup copy of the databases. The hot backup databases are as current as the number of transactions still waiting to be applied.
One of the Calendar Server services launched at startup is csstored. When configured, this service performs automatic backups (either hot backups or archival backups, or both) of your calendar databases.
You can configure csstored for automatic backups when you run the configuration program, csconfigurator.sh. If you choose one or both of the automatic backups at that time, no further configuration steps are necessary.
If csstored is disabled, none of the other daemons that access the database will work. The csstored daemon performs other necessary tasks for the databases. Therefore, the daemon should not be disabled.
When automatic backups are disabled, the circular logging ics.conf parameter, caldb.berkeley.circularlogging, should be set to "yes". This enables purging of old database transaction logs, which conserves disk space.
With automatic backups enabled, csstored automatically manages the number of backup copies retained in your backup database files using a circular backup system.
The csstored process stores backups in your backup database directory until either the maximum number of backup copies have accumulated, or the maximum disk space allowed has been reached. At that point, it purges backup copies (oldest first) until it reaches the minimum number of copies to retain and it is under the disk space threshold.
There are a cluster of ics.conf parameters that control circular backups. These parameters have default values, and do not require further customization. If you wish to tune how backups work in your system, see 21.7 Tuning Automatic Backups.
If you did not configure automatic backups when you ran the configuration file, you can set them up later. This section contains a list of high-level steps necessary for enabling automatic backups for the Calendar Server 6.3 system after the configuration program has already run.
The following is the list of high-level tasks: