Windows Server 2012 Overview : Introducing Windows Server 2012 (part 4) - Planning for availability, scalability, and manageability

Software should be chosen for its ability to support the high-availability needs of the business system. Not all software is compatible with high-availability solutions like clustering or load balancing. Not all software must be compatible, either. Instead of making an arbitrary decision, you should let the uptime needs of the application determine the level of availability required.

An availability goal of 99 percent uptime is usual for most noncritical business systems. If an application must have 99 percent uptime, the application might not need to support clustering or load balancing. To achieve 99 percent uptime means that the application can have about 88 hours of downtime in an entire year, or 100 minutes of downtime a week.

To have 99.9 percent uptime is the availability goal for highly available business systems. If an application must have 99.9 percent uptime, the application must support some type of high-availability solution, such as clustering or load balancing. To achieve 99.9 percent uptime means that the application has less than 9 hours of downtime in an entire year or, put another way, less than 10 minutes of downtime a week.

To evaluate the real-world environment prior to deployment, you should perform integration testing on applications that will be used together. The purpose of integration testing is to ensure that disparate applications interact as expected and to uncover problem areas if they don’t. During integration testing, testers should look at system performance and overall system utilization, as well as compatibility. Testing should be repeated prior to releasing system or application changes to a production environment.

You should standardize the software components needed to provide system services. The goal of standardization is to set guidelines for software components and technologies that will be used in the enterprise. Standardization accomplishes the following:

Software standardization isn’t meant to limit the organization to a single specification. Over the life of a data center, new application versions, software components, and technologies will be introduced, and the organization can implement new standards and specifications as necessary. The key to success lies in ensuring that there is a standard process for deploying software updates and new technologies. The standard process must include the following:

The following checklist summarizes the recommendations for designing and planning software for high availability:

The physical structures and facilities supporting your server room are critically important. Without adequate support structures and facilities, you will have problems. The primary considerations for support structures and facilities have to do with the physical environment of the servers. These considerations also extend to the physical security of the server environment.

Just as hardware and software have availability requirements so should support structures and facilities. Factors that affect the physical environment are as follows:

Temperature and humidity should be carefully controlled at all times. Processors, memory, hard drives, and other pieces of physical equipment operate most efficiently when they are kept cool; between 65 and 70 degrees Fahrenheit is the ideal temperature in most situations. Equipment that overheats can malfunction or cease to operate altogether. Servers should have multiple redundant internal fans to ensure that these and other internal hardware devices are kept cool.

Humidity should be kept low to prevent condensation, but the environment shouldn’t be dry. A dry climate can contribute to static electricity problems. Antistatic devices and static guards should be used in most environments.

Dust and other contaminants can cause hardware components to overheat or short out. Servers should be protected from these contaminants whenever possible. You should ensure that an air-filtration system is in place in the server room or hosting facility that is used. The regular preventive maintenance cycle on the servers should include checking servers and their cabinets for dust and other contaminants. If dust is found, the servers and cabinets should be carefully cleaned.

Few things affect the physical environment more than wiring and cabling. All electrical wires and network cables should be tested and certified by qualified technicians. Electrical wiring should be configured to ensure that servers and other equipment have adequate power available for peak usage times. Ideally, multiple dedicated circuits should be used to provide power.

Improperly installed network cables are the cause of most communications problems. Network cables should be tested to ensure that their operation meets manufacturer specifications. Redundant cables should be installed to ensure the availability of the network. All wiring and cabling should be labeled and well maintained. Whenever possible, use cable management systems and tie wraps to prevent physical damage to wiring.

Ensuring that servers and their components have power is also important. Servers should have hot-swappable, redundant power supplies. Being hot-swappable ensures that the power supply can be replaced without having to turn off the server. Redundancy ensures that one power supply can malfunction and the other will still deliver power to the server. You should be aware that having multiple power supplies doesn’t mean that a server or hardware component has redundancy. Some hardware components require multiple power supplies to operate. In this case, an additional (third or fourth) power supply is needed to provide redundancy.

The redundant power supplies should be plugged into separate power strips, and these power strips should be plugged into separate local uninterruptible power supply (UPS) units if other backup power sources aren’t available. Some facilities have enterprise UPS units that provide power for an entire room or facility. If this is the case, redundant UPS systems should be installed. To protect against long-term outages, gas-powered or diesel-powered generators should be installed. Most hosting and colocation facilities have generators. But having a generator isn’t enough; the generator must be rated to support the peak power needs of all installed equipment. If the generator cannot support the installed equipment, brownouts (temporary outages) will occur.

In addition, access controls should be used to restrict physical access to the server room or facility. Use locks, key cards, access codes, or biometric scanners to ensure that only designated individuals can gain entry to the secure area. If possible, use surveillance cameras and maintain recorded tapes for at least a week. When the servers are deployed in a hosting or colocation facility, ensure that locked cages are used and that fencing extends from the floor to the ceiling.

The following checklist summarizes the recommendations for designing and planning structures and facilities:

Day-to-day operations and support procedures must be in place before you deploy mission-critical systems. The most critical procedures for day-to-day operations involve the following activities:

Monitoring is critical to the success of business system deployments. You must have the necessary equipment to monitor the status of the business system. Monitoring allows you to be proactive in system support rather than reactive. Monitoring should extend to the hardware, software, and network components but shouldn’t interfere with normal systems operations—that is, the monitoring tools chosen should require limited system and network resources to operate.

Without careful analysis, the data collected from monitoring is useless. Procedures should be put in place to ensure that personnel know how to analyze the data they collect. The network infrastructure is a support area that is often overlooked. Be sure you allocate the appropriate resources for network monitoring.

Resources, training, and documentation are essential to ensuring that you can manage and maintain mission-critical systems. Many organizations cripple the operations team by staffing minimally. Minimally staffed teams will have marginal response times and nominal effectiveness. The organization must take the following steps:

Every change to hardware, software, and the network must be planned and executed deliberately. To do this, you must have established change-control procedures and well-documented execution plans. Change-control procedures should be designed to ensure that everyone knows what changes have been made. Execution plans should be designed to ensure that everyone knows the exact steps that were or should be performed to make a change.

Change logs are a key part of change control. Each piece of physical hardware deployed in the operational environment should have a change log. The change log should be stored in a text document or spreadsheet that is readily accessible to support personnel. The change log should show the following information:

You should have well-defined backup and recovery plans. The backup plan should specifically state the following information:

Backups should be monitored daily to ensure that they are running correctly and that the media is good. Any problems with backups should be corrected immediately. Multiple media sets should be used for backups, and these media sets should be rotated on a specific schedule. With a four-set rotation, there is one set for daily, weekly, monthly, and quarterly backups. By rotating one media set offsite, support staff can help ensure that the organization is protected in case of a disaster.

The recovery plan should provide detailed step-by-step procedures for recovering the system under various conditions, such as procedures for recovering from hard disk drive failure or troubleshooting problems with connectivity to the back-end database. The recovery plan should also include system design and architecture documentation that details the configuration of physical hardware, application-logic components, and back-end data. Along with this information, support staff should provide a media set containing all software, drivers, and operating system files needed to recover the system.

You should practice restoring critical business systems using the recovery plan. Practice shouldn’t be conducted on the production servers. Instead, the team should practice on test equipment with a configuration similar to the real production servers. Practicing once a quarter or semiannually is highly recommended.

You should have well-defined, problem-escalation procedures that document how to handle problems and emergency changes that might be needed. Some organizations use a three-tiered help desk structure for handling problems:

All crisis situations and emergencies should be responded to decisively and resolved methodically. A single person on the emergency response team should be responsible for coordinating all changes and executing the recovery plan. This same person should be responsible for writing an after-action report that details the emergency response and resolution process used. The after-action report should analyze how the emergency was resolved and what the root cause of the problem was.

In addition, you should establish procedures for auditing system usage and detecting intrusion. In Windows Server 2012, auditing policies are used to track the successful or failed execution of the following activities:

You should have an incident-response plan that includes priority escalation of suspected intrusion to senior team members and provides step-by-step details on how to handle the intrusion. The incident-response team should gather information from all network systems that might be affected. The information should include event logs, application logs, database logs, and any other pertinent files and data. The incident-response team should take immediate action to lock out accounts, change passwords, and physically disconnect the system if necessary. All team members participating in the response should write a postmortem report that details the following information:

The team leader should write an executive summary of the incident and forward this to senior management.

The following checklist summarizes the recommendations for operational support of high-availability systems: