Why Using Messaging Server 64-bit Edition Is Better

This information describes the reasons to use Messaging Server 64-bit Edition instead of the 32-bit Edition, as well as some Messaging Server tuning considerations.

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Using Messaging Server 64-bit Edition

Beginning with the release of Messaging Server 6.3, on Solaris Operating System (Solaris OS) software, you have had the option of installing the 64-bit version of Messaging Server. The Communications Suite Product team now recommends that you install the 64-bit Edition for new installations on Solaris OS, and upgrade your existing 32-bit Messaging Server deployments on Solaris OS to the 64-bit version, as time permits. You should no longer install the 32-bit version of Messaging Server on Solaris OS software.

Reasons to use or switch to Messaging Server 64-bit Edition include:

• Solves the problems of large store.idx files described in Large store.idx Files Issue in Messaging Server 32-bit Edition.
• Offers the ability to run a reasonable number of imapd processes instead of running dozens of them.
• Better utilizes LDAP cache (see also LDAP Cache Tuning in Messaging Server).

Large store.idx Files Issue in Messaging Server 32-bit Edition

Prior to Messaging Server 64-bit Edition, you had to increase the number of imapd processes as a workaround for the 32-bit address space limitation. As folders grew, the size of store.idx files grew and the 32-bit address space limitation became a larger problem. The workaround was to reduce maxsessions and increase numprocesses. Now, the solution is to upgrade to Messaging Server 64-bit Edition. (The current version is Messaging Server 7 Update 2.) When you install or upgrade to the 64-bit Edition, you no longer need this workaround for large store.idx files.

Note If you upgrade to Messaging Server 64-bit Edition, the upgrade process does not change your existing Messaging Server configuration. The default, out-of-the-box configuration has always set numprocesses to 1. The Messaging Server 64-bit upgrade retains your "customized" configuration. To remove the previously mentioned workaround from your system, set numprocesses back to 1 (or 4) and set maxsessions high enough to meet your concurrent connection requirements. (You can use the counterutil command to monitor your maxconnections.)

Miscellaneous

• If you are migrating from a version of Messaging Server prior to 6.3 to Messaging Server 6.3 64-bit or Messaging Server 7 64-bit, refer to mshttpd Changes Starting with Messaging Server 6.3.
• The backup file format has not changed from the 32-bit Edition to the 64-bit Edition, so you can use imsbackup on a 32-bit server and imsrestore on the 64-bit server with the same backup files.
• The Messaging Server 6.3 cluster agent package is not compatible with the 64-bit Edition. Use the Sun Cluster Messaging HA package from the Messaging Server 7 release.
• Increasing maxsessions means using more file descriptors. In Messaging Server 6.3, you might need to work around CR 6767802 by adding a ulimit -n command to the start-msg script.
• If you have installed Solaris 10 OS for x86 Platforms and you use SNMP to monitor Messaging Server, you lose that functionality if you use Messaging Server 64-bit Edition. At issue are bugs in the native Solaris SNMP support on the Solaris 10 OS for x86 Platforms.
• Third-party MTA plugins might not be available in 64-bit versions. Contact your third-party vendor for further assistance in obtaining a 64-bit compatible plugin. As of Messaging Server 7 Update 3, very limited support is provided for the use of a single 32-bit, spam-filter plugin in a 64-bit Messaging Server installation. Use of a 32-bit plugin is not recommended and customers should use a 64-bit plugin for best compatibility.
• Starting with Messaging Server 7 Update 3, the 64-bit Edition enables the number of connections for MTA processes (MAX_CONNS in dispatcher.cnf) to be greater than 50 (RFE 6463522), but you will also need to increase MAX_SERVER_THREADS in the associated channel's SMTP channel option file (usually tcp_local_option) to the same value specified in MAX_CONNS.

Issues to Keep in Mind

• The 64-bit Edition product binaries and binary data files require more disk space than those from the 32-bit Edition.
• RAM consumption for the 64-bit Edition is generally higher for the same load, but this consumption is probably more than offset by enabling fewer processes to serve the same workload.
• Older 32-bit hardware should not be used, although it might still be adequate for smaller deployments, MTAs, or MMPs.
• Customers with 32-bit plugin code might have trouble getting it rebuilt for 64-bit, especially for third-party code.

Nevertheless, these issues are more than offset by the positive benefits of the 64-bit Edition.