47 Managing Message Store Partitions and Adding Storage

Message Store Partition Overview

Mailboxes are stored in message store partitions, an area on a disk partition specifically devoted to storing the message store. Message store partitions are not the same as disk partitions, though for ease of maintenance, it is recommended that you have one disk partition and one file system for each message store partition. Message store partitions are directories specifically designated as a message store.

User mailboxes are stored by default in the store_root/partition/ directory (see "Classic Message Store Directory Layout"). The partition directory is a logical directory that might contain a single partition or multiple partitions. At start-up time, the partition directory contains one subpartition called the primary partition.

You can add partitions to the partition directory as necessary. For example, you might want to partition a single disk to organize your users as follows:

store_root/partition/mkting/
store_root/partition/eng/
store_root/partition/sales/

As disk storage requirements increase, you might want to map these partitions to different physical disk drives.

You should limit the number of mailboxes on any one disk. Distributing mailboxes across disks improves message delivery time (although it does not necessarily change the SMTP accept rate). The number of mailboxes you allocate per disk depends on the disk capacity and the amount of disk space allocated to each user. For example, you can allocate more mailboxes per disk if you allocate less disk space per user.

If your message store requires multiple disks, you can use RAID (Redundant Array of Inexpensive Disks) technology to ease management of multiple disks. With RAID technology, you can spread data across a series of disks but the disks appear as one logical volume so disk management is simplified. You might also want to use RAID technology for redundancy purposes; that is, to duplicate the store for failure recovery purposes.

To Add a Message Store Partition

When adding a partition, you specify both an absolute physical path where the partition is stored on disk, and a logical name (called the partition nickname).

The partition nickname enables you to map users to a logical partition name regardless of the physical path. When setting up user accounts and specifying the message store for a user, you can use the partition nickname. The name you enter must be an alphanumeric name and must use lowercase letters.

To create and manage the partition, the user ID used to run the server must have permission to write to the location specified in the physical path.

• Command Line, To add a partition to the store at the command line: The location of message files is controlled by setting the partition:partition_name.messagepath option, where partition_name is the logical name of the partition.

  msconfig set partition:partition_name.messagepath path
  

  path indicates the absolute path name where the partition is stored. To specify the path to the primary partition:

  msconfig set partition:primary.path path
  

To Change the Default Message Store Partition

The default partition is the partition used when a user is created and the mailMessageStore LDAP attribute is not specified in the user entry. The mailMessageStore LDAP attribute, which specifies a user's message store partition, should be specified in all user entries so that a default partition is not necessary. In addition, the default partition should not be changed for load balancing or any other reason. It is invalid and dangerous to change the default partition while there are still users depending on the default partition definition.

If it is absolutely necessary to change the default partition, make sure that all users on the old default partition (the one being left behind) have their mailMessageStore attribute set to their current partition (which will no longer be the default), before changing the definition of default with the store.defaultpartition option.

Adding More Physical Disks to the Message Store

The Messaging Server message store contains the user mailboxes for a particular Messaging Server instance. The size of the message store increases as the number of mailboxes, folders, and log files increase.

As you add more users to your system, your disk storage requirements increase. Depending on the number of users your server supports, the message store might require one physical disk or multiple physical disks. Messaging Server enables you an add more stores as needed.