Messaging Server and Mailstore Best Practices - "Muling" Over Your Options

When it comes to setting up the disk partitions on your mailstore, the Messaging Server experts agree: spread your mailboxes out across multiple partitions. The benefits include:

  • Faster times to back up and restore mailboxes
  • Less risk of data loss (you lose only those mailboxes on a particular partition instead of all mailboxes on a single partition)
  • Increased performance and scalability (assuming the partitions are accessing separate spindles)
  • The ability to run many imsbackup instances in parallel, one per partition, which can help to back up many gigabytes of mail in the 6-8 hours you normally have
For information on configuring mailstore partitions, see Chapter 18, Managing the Message Store, in the Sun Java System Messaging Server Administration Guide.

Deciding on The Number of Partitions

To decide upon the number of partitions to create, consider the following:
  • Partitions are logical objects, so equate the partition to a file system. Because of this, your partitions depend on the file system type.
  • With UFS you have a limited set of inodes to manage. Pay attention to the expected mailbox population (number of mails, attachments, minimum and maximum size, and so on) to estimate the number of inodes needed. Based on that, define your file systems/partitions. In the Solaris OS environment, use the df -o i command to see the inodes your file systems have.
  • As a best practice, limit a single partition's size to less than 1 TByte. It is further suggested that you use no more than 900 GB per partition.

Quick Primer on Configuring Mailstore Partitions

To configure a mailstore partition, you make the mailstore aware of the partitions by using the configutil command, for example:

configutil -o store.partition.nickname.path -v path

where nickname is the logical name of the partition and path indicates the absolute path name where the partition is stored.

Next, on the user directory entry, set the mailmessagestore attribute to the nickname of the partition.

Additionally, you can set the default partition (if the user doesn't have a mailmessagestore attribute) by using the configutil store.defaultpartition attribute as well as the default primary partition with the following command:

configutil -o store.partition.primary.path -v path

Comments:

The main limitation of UFS around mailstore partitions is that if you create a file system over ~ 1 terabyte (or with the option to grow over a terabyte) then it reduces the inode count to 1 million per terabyte, thus severly limiting the number of files. If you create a UFS file system under 1 TB, it will have a standard inode/bytes ratio (by default 1 inode per 8k, but you can adjust it during creation). If you want to have individual mail partitions over 1TB, you really need to look at using ZFS, VXFS, or a supported NAS filer. More details on UFS limitations are at: http://docs.sun.com/app/docs/doc/817-5093/6mkisoq58?a=view#fsoverview-18

Posted by William Hathaway on December 20, 2006 at 11:02 PM MST #

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