Zimbra NG Modules/Zimbra NG HSM/Secondary volumes on Amazon S3

Zimbra NG HSM - Secondary Volumes on Amazon S3

Zimbra NG HSM - Secondary Volumes on Amazon S3

Starting from Zimbra NG Modules 2.4.0, secondary volumes created with Zimbra NG HSM can now be hosted on Amazon S3 buckets, effectively moving the largest part of your data to a secure and durable cloud storage.

Infrequent Access storage class

Zimbra NG HSM is compatible with the "Amazon S3 Standard - Infrequent access" storage class, and will set any file larger than the "Infrequent Access Threshold" value to this storage class.

For more information about Infrequent Access please refer to the official Amazon S3 Documentation.

Other S3-compatible services

While any storage service compatible with the Amazon S3 API should work out of the box with Zimbra NG HSM, only the Amazon S3 service is officially supported at the moment.

Local Cache

This feature requires a local directory to be used for item caching, which must be readable and writable by the "zimbra" user.

Such directory must be created manually and its path must be entrered in the "HSM" section of the Zimbra NG Modules Administration Zimlet in the Zimbra Administration Console.


Failing to correctly set the cache directory will cause items to be unretrievable, meaning that users will get a "No such BLOB" error when trying to access any item stored on an S3 volume.

Bucket setup

Zimbra NG HSM doesn't need any dedicated setting or configuration on the S3 side, so setting up a bucket for your volumes is pretty easy - it's not even necessary to create a dedicated bucket.

All you need to start storing your secondary volumes on S3 is:

  • An S3 bucket. You need to know the bucket's name and region in order to use it.
  • A user's Access Key and Secret.
  • A policy which grants the user full rights on your bucket.

Bucket paths and naming

Files are stored in a bucket according to a well-defined path, which can be customized at will in order to make your bucket's contents easier to understand even on multiserver environments with multiple secondary volumes:

/Bucket Name/Destination Path/[Volume Prefix-]serverID/

The Bucket Name and Destination Path are not tied to the volume itself, and there can be as many volumes under the same destination path as you wish.

The Volume Prefix, on the other hand, is specific to each volume and it's a quick way to differentiate and recognize different volumes within the bucket.

S3 Buckets

Instead of adding the bucket's data each time you add a new secondary volume, you can save it on the Zimbra Administration Console at Configure > Global Settings > S3 Buckets.


Creating a secondary volume on Amazon S3

  • Click on the "HSM" entry of the Zimbra NG Modules Administration Zimlet in the Zimbra Administration Console.
  • Under the "Secondary Volumes" list, click on "Add"


  • Select "S3 bucket"


  • Enter the volume's name and prefix, then either add a bucket's information or load those from the ones saved in the Global Settings. Define whether to use the Infrequent Access storage class and if so set its size threshold.


  • Define whether the new volume is set as Current or not and click "Finish" to create the new volume.


Zimbra NG Modules


Latest Version: 8.8

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