Zimbra Storage Volumes
A policy is stored in the global and server attribute zimbraHSMPolicy. HSM polices are search-based to take advantage of Zimbra's advanced search capabilities. See /opt/zimbra/docs/query.txt. The zimbraHSMPolicy attribute is multi-valued which is used in the creation of multiple policies. All polices are evaluated during a single HSM run.
The default HSM policy will move document and message types older than 30 days from the active primary message volume to the active secondary storage volume.
zmprov gs `zmhostname` zimbraHSMPolicy zimbraHSMPolicy: message,document:before:-30days