When planning server system disk space, you need to be sure to include space for operating environment software, Messaging Server software, and message content and tracking. Be sure to use an external disk array if availability is a requirement. For most systems, external disks are required for performance because the internal system disks supply no more than four spindles.
In addition, user disk space needs to be allocated. Typically, this space is determined by your site’s policy.
Your deployment planning needs to include how you want to back up the Message Store for disaster recovery. Messaging Server supports Solstice Backup (Legato Networker), the imsbackup utility, and file system snapshot backup. You might want to store your backup media remotely. The more frequently you perform a backup, the better, as long as it doesn’t impact server operations.