Zimbra Incremental Migration: an experience

Some days ago, I managed to migrate our company's Zimbra mail system to a new server.  Since there were so many messages to move, the migration was a hard work, and caused a lot of troubles.

A brief description of the task:

• The old server: CentOS 5.5 x86_64, ZCS 7.2.0
• The new server: CentOS 6.3 x86_64, ZCS 8.0.0
• Mail accounts: 1500, messages: 4 millions, storage: 600 GB
• Bandwidth between two servers: 100 Mbps

I followed the method described in ZxBackup: Incremental migration with ZeXtras Backup.  The process comprised the following steps:

1. Backup of all messages on the old server: about 4 million items, backup time: 3 days.
2. Synchronization of backup data to the new server: data size: 320GB, files: 6.4 million, transfer time: 1 day.
3. Restore of old messages on the new server: restore time: 5 days.
4. Incremental backup and restore recent messages since last backup
5. Switch of the mail flow to the new server
6. Incremental backup and restore recent messages since last backup