Hierarchical Storage Management for Zimbra Messages

Hierarchical Storage Management (HSM) allows you to configure storage volumes for older messages. To manage your email storage resources, you can implement a different HSM policy for each mailbox server. Messages and attachments are moved from a primary volume to the current secondary volume based on the age of the message. The messages are still accessible. Users are not aware of any change and do not see any noticeable difference when opening an older message that has been moved.

Setting up  HSM Volume

Before you can set up HSM, the current secondary volume must exist. See Volume Management an overview about adding volumes.

HSM is configured from the Servers>Volume tab. The HSM volume type is set as Secondary Message, and the threshold to move messages is set. Messages are moved to the secondary storage volume, based on the timestamp of the message. The default is to move messages older then 30 days.

How to set up HSM:

  1. Create a current secondary volume.

  2. On the administration console,  select the mailbox server and click Edit.

  3. Go to the  Servers>Volumes tab. and click Add New Volume.

  4. Enter the HSM secondary volume name, volume root path and select the volume type to be Secondary Message. To save space the default Compress Blobs checkbox is enabled with a default compression threshold of 4096 bytes.

  5. Click Make Current.

  6. Click Save.

  7. Configure the Message age threshold for HSM.  The default is 30 days.  

  8. Note: The message age threshold can also be set in Global Settings.

Running HSM Process

You can manually start a session to move messages to a secondary volume, and you can create a HSM job in your cron table to schedule HSM sessions. HSM sessions should be scheduled to run on a regular basis

The first time you run the HSM session, you should schedule the session to run in off-peak hours.  When you start the HSM session, the process iterates through the mailboxes on the server, moving messages that meet the threshold age limit. Depending on how many messages will be moved, the session could take some time.  

To start an HSM session

  1. Select the server

  2. Click HSM, on the Server's toolbar.

  3. In the dialog that opens, click Start HSM Session.

  4. Click OK, to close the dialog. The session continues to run.

While the session is running,  a progress bar on the HSM dialog shows how many mailboxes have been processed and how man BLOBS have been moved. You can open the HSM dialog to see the current status of the session.

Aborting an HSM Session

A HSM session can be aborted from the HSM dialog, at any time. Clicking Abort stops the session.  If all the messages in a mailbox being processed were not moved before you clicked Abort, no messages from that mailbox are moved from the primary volume.  Messages for mailboxes that have completed the move to the secondary volume are not moved back to the primary volume.