Beware Size Limits in Different Versions of Exchange Server
Kieran McCorry states in his article "Get a Grip on Exchange Data Management" (April 2005, InstantDoc ID 45623) that, "an Exchange Server 2003 or Exchange 2000 Server machine can contain as many as five databases within an SG \[storage group\] and can hold as many as four SGs; thus, one server can contain as many as 20 databases. Established best practice advises against letting your databases exceed 40GB each so that backups—and more important, restores—can occur within acceptable time limits." This statement is true for Exchange 2003 Enterprise Edition and Exchange 2000 Enterprise Edition. However, both Exchange 2003 Standard Edition and Exchange 2000 Standard Edition, although significantly less expensive than their Enterprise Edition counterparts, have much stricter size limits. Standard Edition has a limit of only one Mailbox store and one Public Folder store. And each of those stores has a 16GB size limit. If this limit is exceeded, the store will dismount and its contents will be unavailable until enough data is removed to bring the store back under the limit. I think these differences in size limits are important to note because of the difference in cost between the enterprise and standard versions. Administrators who want to save money and purchase the Standard Editions need to keep the size limitations in mind when planning their deployments.

Hardening Windows for Specific Needs
In her article Hey Microsoft!: "How Trustworthy Is ISA Server 2004?" (April 2005, InstantDoc ID 45594) Karen Forster asked readers what Microsoft could do to raise our comfort level with the company's security efforts. I'd like to see Microsoft harden Windows similarly to Linux. Such an OS would be great to run ISA Server on. Yes, you have to configure Linux to harden it, but doing so is possible. I've hardened Windows with the new security tools, but I'd like to see Microsoft change the code for an appliance-type application. Microsoft products work very well inside the network, but I'd like to see a DMZ type of OS for FTP, ISA Server, and IIS. An OS that provides a specific need for a particular hardware setup (such as Dell or HP) would be the best for the DMZ and give Linux a run for its money. Microsoft should also be looking at an Intrusion Prevention System (IPS) addition to its security procedures. I've built Linux/Snort boxes to help me track traffic, but I'd like to see Microsoft jump into this arena. The skill and knowledge that Microsoft can bring to this area of security would benefit all systems engineers.

Virtual Server Clustering
Michael Otey's article "Virtual Server 2005 Cluster Setup Kit" (May 2005, InstantDoc ID 45901) is just one more reason why I never let my subscription to Windows IT Pro expire. Clients and peers have often looked at me with that "It's never going to work" look when I mention clusters using virtual servers. Thanks to Michael for validating the concept. His article will convince more of our clients to look at this option for SQL Server availability.

Regarding "Virtual Server 2005 Cluster Setup Kit," what if the physical box crashes? You've got both virtual machines (VMs) in the cluster on the same physical box. Can Virtual Server 2005 do a cluster with two VMs on two different physical host servers? VMware ESX can.

Virtual Server 2005 supports clustering only on a single system. The purpose of using Virtual Server to set up a cluster is to enable you to create a lab/test clustering environment or to practice the steps of setting up a cluster before you set up the cluster on live hardware. You wouldn't want to use a Virtual Server cluster on a single system for high availability. Clustering is a technology that protects against server failure—attempting to use it for high availability on one system would defeat that purpose.

ESX Server is an entirely different class of virtual machine. It runs directly on the hardware and doesn't require a host OS, as is the case with Virtual Server 2005 or VMware's other VM server product, GSX Server. When used in combination with Virtual Center, ESX Server does offer the capability of moving VMs between servers. However, ESX Server is a much more expensive product than either Virtual Server 2005 or GSX Server.