Zimbra Backup Methods

•	The standard backup method is to run a weekly full backup session and daily incremental backup sessions to back up all mailboxes daily. The standard backup method is appropriate for enterprise deployments where full backups are run during non-working days.

•

The auto-grouped backup method is recommended for large ZCS environments where running a full backup of all accounts at one time would take too long.The auto-grouped backup method runs a full backup session for a different group of mailboxes at each scheduled backup. The system administrator configures the interval that backups should run and configures the number of groups that backups are made up of. ZCS then automatically backs up mailboxes in groups over the interval specified.

A full backup process backs up all the information needed to restore mailboxes, including the LDAP directory server, database, index directory, and message directory for each mailbox.

When backing up shared messages, the backup process looks to see whether a file representing a message already exists in the backup. If it does, it flags this object as such and does not copy its content again.

An incremental backup process backs up the LDAP data and gathers all the redo logs written since the last incremental backup. If the incremental backup process finds no previous full backup for a mailbox, a full backup is performed on that mailbox.

Incremental backups move the redo logs to the backup directory. The redo logs are a journal of every activity that has taken place. They contain a full copy of all messages delivered, as well as metadata such as tags, contacts, and conversations.

These backup files can be used to restore the complete mailbox server or individual mailboxes so that account and message data is completely restored.

The LDAP directory is backed up as part of either the full or incremental backup process. All accounts, domains, servers, COS, and other data are backed up.

Each mailbox server generates redo logs that contain every transaction processed by that server. If an unexpected shutdown occurs to the server, the redo logs are used for the following:

•	To ensure that no uncommitted transactions remain, the server reads the current redo log upon startup and re-executes and completes any uncommitted transactions.

•	To recover data written since the last full backup in the event of a server failure.

When the server is restored, after the backed up files are fully restored, any redo logs in the archive and the current redo log in use are replayed to bring the system to the point before the failure.

The auto-grouped backup method is designed for very large ZCS environments where backing up all accounts can take a long time. Auto-grouped backups combine full and incremental backup functions. This eliminates the need for incremental backups. Each auto-grouped session runs a full backup of the targeted group of mailboxes.