ZCS 8.8 Article ZCS 8.8

What is the External Restore?
The External Restore is one of the Restore Modes of ZxBackup.

How does it work?
The External Restore adds to the current Zimbra server all the data, metadata and configurations stored on an External Backup.
This also applies to Next Generation Migration Tool exports, allowing you to import domains from other servers. The workflow of the import procedure is the following:


  • Operation Started" notification
  • Read Server Backup Data
  • Create empty Domains
  • Create needed COS (only those effectively used by the imported accounts)
  • Create empty DLs
  • Create empty Accounts
  • Restore all Accounts' attributes
  • Restore all Domains' attributes
  • Restore all DLs' attributes and share informations


  • Restore all Items


  • Restore all Mountpoints and Datasources

Before you start

  • If you are working on a Multistore environment be sure to have read and understood the Multistore informations page before starting an External Restore.
  • If Next Generation Backup is already initialized on the destination server, disable the RealTime Scanner in order to improve both memory usage and I/O performances.
  • In order to reduce the I/O overhead and the amount of disk space used for the migration, advanced users may tweak or disable Zimbra's RedoLog for the duration of the import.
  • In order to further reduce the amount of disk space used, it's possible to enable compression on your Current Primary Volume before starting the import. If you do not wish to use a compressed Primary Volume after migration, it's possible to create a new and uncompressed Primary Volume, set it to "Current" and the switch the old one to "Secondary". All of this can be done using Next Generation Powerstore.

Running an External Restore
Via the Next Generation Administration Zimlet

  • Click the Backup tab (be sure to have a valid License)

Zimlet Panel b.png

  • Click on the "Import Backup" button under "Import/Export" to open the Import Backup wizard.

ImB 01 b.png

  • Enter the Destination Path in the textbox and press Forward. Next Generation will check if the destination folder contains a valid Next Generation backup and whether the 'zimbra' user has Read permissions or not.

ImB 02 b.png

  • Select the domains you want to import and press Forward.

ImB 03 b.png

  • Select the accounts you want to import and press Forward.

ImB 04 b.png

  • Verify all your choices in the Operation Summary window. You can also add additional email addresses to be notified when the Restore operation is finished. Please notice that the Admin account and the User who started the Restore procedure are notified by default.

ImB 05 b.png

Via the Next Generation CLI
To start an External Restore operation, the "doExternalRestore" command is available:

   zxsuite backup doExternalRestore {source_path} [attr1 value1 [attr2 value2...]]


NAME                          TYPE                 EXPECTED VALUES    DEFAULT
source_path(M)                Path                                    
accounts(O)                   Account Name[,..]                       all
domains(O)                    Domain Name[,..]                        all
filter_deleted(O)             Boolean              true|false         true
skip_system_accounts(O)       Boolean              true|false         true
skip_aliases(O)               Boolean              true|false         false
skip_distribution_lists(O)    Boolean              true|false         false
provisioning_only(O)          Boolean              true|false         false
skip_coses(O)                 Boolean              true|false         false
notifications(O)              Email Address                           

(M) == mandatory parameter, (O) == optional parameter

Usage example:

zxsuite backup doexternalrestore /opt/zimbra/backup/restorePath/ accounts john@example.com,jack@example.com domains example.com filter_deleted false skip_system_accounts false
Restores the example.com domain, including all system accounts, and the john@example.com and jack@example.com accounts from a backup located in /opt/zimbra/backup/restorePath/

Speeding up the restore through multithreading
Staring from Next Generation 2.4.3, the concurrent_accounts parameter allows to restore multiple accounts at the same time, thus greatly speeding up the restore process. This feature is not available via GUI.
Albeit resource consumption does not grow linearily with the number of accounts restored at the same time, it can easily become taxing - start from a low number of concurrent accounts, raising it according to your server's performances.

Usage example:

zxsuite backup doExternalRestore /tmp/external1 domains example0.com,example1.com concurrent_accounts 5

Restores the example0.com and example1.com domain, excluding system accounts, restoring 5 accounts at same time from a backup located in /tmp/external1

After the Restore: Message Deduplication
Running a Message Deduplication operation through Next Generation Powerstore is highly suggested in order to save precious storage space.

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