Scalability and Mobility

Organizations generally grow in size. However, they can also shift laterally with personnel from one department being redeployed to another department. This kind of growth can create considerable scalability headaches for the IT department. Effectively, demand for a particular server, such as the email security appliance, can grow dramatically overnight. Other influences, such as an increase in email due to a promotional activity, or a sharp increase in spam due to certain spamming campaigns, can also increase the load on a given appliance. The ability to be able to increase the physical characteristics of the platform or migrate an appliance from one server to another larger one, provides a fast and effective mechanism for dealing with demand. Being able to instantiate an additional anti-spam server can also assist with short-term demand and offers a fast route to load-balancing.

Attempting to prebuild this type of architecture using only physical appliances can create considerable space and cost difficulties as it requires that the organization plan for the largest throughput and build it out accordingly. This also leaves no possibility to handle peak demand in a more rational way, by having additional capacity which can be deployed for specific tasks. For example, it may be that a given company has a large web site promotion which is due to come to an end. In addition, the result of the campaign has resulted in a significant increase in email messages received. As the number of "hits" on the website starts to fall off, spare capacity can be redeployed to deal with the additional volume of inbound email by reconfiguring the virtual appliances or by creating additional instances of the email security appliance and removing instances of the web site.

The ability to be able to lift an application from one virtual machine and deploy it on another provides a powerful framework for rolling out services across the organization. As the head count grows, new virtual machines can be instantiated and the number of virtual machines driving a specific application can be increased to meet the demand. Likewise, reduced demand for certain applications can be addressed by removing the image from one or more virtual machines, freeing up these resources for other applications. From a geographic perspective, new applications can be deployed at remote sites simply by copying the virtual image to the server or servers at the remote site.

When a specific server needs to be taken offline for whatever reason, the virtual images executing on that server can be migrated to a new virtual machine without issues of platform version or operating system version.

Mobility is absolutely essential for the proper operation of an application group. It can be next to impossible to move a running user base from one physical appliance to another without significant down-time. In the case of mail antispam appliances, user configuration must be migrated, along with live mail data and quarantine files, black lists, white lists, and other elements of the configuration. For a large group of users, these characteristics are changing in a non-deterministic way and at an alarming frequency. Small companies and large alike will often schedule appliance transitions months in advance. The new appliance will be deployed for a month or two while the administrator tries to find a window to migrate the user base. For most companies, these windows fall on weekends when demand is low. However, many organizations find it difficult to find quiet periods even on weekends. Again, mail is a good example. Users will often check their email on the road, from home, and even on vacation. The unavailability of the mail system for even two days across a weekend can be problematic. Removing the mail security appliance from the picture can result in clogged mailboxes in a matter of hours.

Mobility is a difficult problem to solve. Most often, the solution is to duplicate the data sets on the old server and the new server over a period of time. Mailboxes must be migrated in their entirety, including any hidden extras such as personal blacklists, personal whitelists, filter rules and so on. Sometimes the application will provide tools for exporting and importing the data sets, but again this can raise issues unless the new appliance has an identical release of the mail software or at least a mechanism for realigning the data sets between versions.

Being able to encapsulate the entire email antispam and antivirus appliance into a single image makes mobility and scalability a relatively trivial exercise. The image is simply "removed" from the old virtual server and redeployed on the new one. Within minutes, the user community is accessing their email on the new server using the same password and same features as always.