Monitoring and Maintaining Server Availability
| Periodic monitoring of your Windows Server 2003 network is important to the process of optimization. Monitoring helps to overcome the feeling-based assessment of your users. For example, by comparing current network performance against a previously established baseline, you have more information than the anecdotal "The network is slow today!" on which to base your actions. By gathering current information and comparing it against established norms for your systems (a baseline), you can detect bottlenecks, identify those system components that are slowing down server performance, and fix them before they become a problem to your users. The importance of establishing a baseline before beginning to monitor performance can't be overstated. Although there are some guidelines as to what absolute performance numbers indicate , it is as you compare current performance against past performance (the baseline) that you will really be able to evaluate how well current demand is being met and whether you require more resources on your server. In addition, it is imperative that a baseline be established before problems begin to occur. If users are already beginning to complain, "The network is slow," it is too late to establish a baseline because the statistics gathered will include whatever performance factors are contributing to the dissatisfaction. A baseline is a set of typical readings that define "normal" for your servers, client computers, or network under various operating conditions, such as no load, moderate load, and heavy load. Of course, what is normal is obviously open to interpretation, but you could say that normal is a server providing users with what they want in a time frame that they think is reasonable. By creating baselines early on, you have something that you can later look back at and compare current server operating conditions to. If your system is already to the point where you are seeing system degradation, it is really too late to establish a baseline. To establish a baseline, you pick a time (or duration of time) that represents typical user interaction with the server. Then you create a log of important counters for the duration you have determined. Some of the more commonly used (and recommended) counters are summarized in Table 10. Table 10. Counters to Monitor for Baselining and Bottleneck Troubleshooting
At a minimum, you must perform periodic monitoring on the following areas of your Windows Server 2003 computers: the hard disk(s), processor(s), memory, and network adapter(s). Regardless of which type of services the server is providing, these four areas interact to make your server efficient (thereby appearing fast) or inefficient. The actual speed or efficiency of each of the components varies in importance depending on the application. In some applications, memory is more important than processor speed or availability; in other applications, disk speed and availability are more important than fast network access. Recognizing the need to be able to monitor the performance (and thus the health) of servers and client computers, Microsoft built the Performance Monitor into Windows Server 2003. Whether you are looking for real-time graphical views or a log you can peruse at your convenience, the Performance Monitor can provide the type of data you need to evaluate performance and recommend system modification if necessary. On a daily basis, you may not want to monitor the full group of counters that were listed previously in Table 10. The counters in Table 11 present a smaller, and thus easier to manage, group of counters that you might consider monitoring on a daily basis to get a quick snapshot of your system and network performance. Table 11. Counters to Monitor on a Daily Basis
The following are some of the most common causes of bottlenecks that you might encounter while troubleshooting your network:
After you have identified a problem, you should take care to avoid creating new problems while correcting the old one. You should make one change at a time to avoid masking the impact of changes. After each change, you should perform additional monitoring to determine the result and the effect of the change and reevaluate the status and condition of the previously identified problem(s). In addition, you can compare the performance of applications that are run over the network to their performance when run locally to determine how the network is affecting performance. You should keep in mind the following general points when working with Windows Backup:
When you use the volume shadow copy, a copy of the original volume is created instantly at the time you initiate the backup. Data is then subsequently backed up to the backup media from this shadow copy instead of the original files. This new technology provides a means to back up open files that were in use at the time of the backup being initiated. When you use volume shadow copy, files that would normally be skipped during the backup are instead backed up in their current state (at the time of the shadow copy creation) and thus appear closed on the backup media. Any applications that are running during the backup process can continue to run during the backup process. After the backup has been completed, the shadow copy is deleted. The volume shadow copy feature requires the NTFS file system to be in use and can be disabled if you want. Another new use of the volume shadow copy feature is to create "snapshots" of shared network folders that can be used to roll back to a previous version of a file. Automated System Recovery (ASR) is an advanced restoration option of the backup utility that you can use to restore your system if other disaster recovery methods fail or are not available for use. Using ASR, you can restore the operating system to a previous state, which allows you to start Windows Server 2003 in the event that other methods do not work. You should always consider ASR your last resort for recovery, after Safe Mode, the Recovery Console, and Last Known Good Configuration (LKGC). You should make a point to keep your ASR media up to date as you make configuration changes to your computer to minimize the amount of recovery required should you ever need to use ASR. ASR is a two-part process that uses a startup floppy disk to boot the Windows Server 2003 computer and a backup file (that must be accessible during ASR restoration) containing the system state, system services, and all disks associated with the operating system components. The startup disk contains information about the backup, the disk configurations, and the way the restoration is to be accomplished. You should perform an ASR recovery only after all other available methods to start the server normally have failed. However, before starting the procedure, you need to locate the following items and have them readily available to you:
The usefulness of volume shadow copies is not just limited to its use within Windows Backup to create backups of open files; this feature also provides you with a way to archive copies of data over time, allowing users to locate and restore a specific file if they want. After the necessary configuration has been completed and the required software installed, users can view the volume shadow copies of shared network folders, including any previous versions in existence. Users can then copy any or all of the older files, allowing them to effectively restore a backup copy of the files from an earlier time. As you might imagine, volume shadow copies can provide a number of benefits to your network users ”the least of which is the ability to restore an older version should the current version of a file become corrupt or be deleted beyond recovery. You also can compare different versions of files to see what changes have occurred over time. Files contained in a volume shadow copy are read-only while archived, preventing them from being modified and thus nullifying the benefits of the volume shadow copy. After a file has been extracted from a volume shadow copy archive, it can be modified or moved to any location desired for editing. Shadow copies are disabled by default but can be enabled and configured from the Shared Folders node of the Computer Management console. Windows Server 2003 allows for only 64 volume shadow copies of a specific shared folder. When this limit is reached, the oldest copy is deleted to make room for a newer copy. Before your network clients can take advantage of this technology, they must have the Volume Shadow Client software installed. The client software is available on your Windows Server 2003 computer in the %systemroot%\system32\clients\twclient\ folder. After you've configured volume shadow copies, Windows Server 2003 computers and client computers with the Volume Shadow Client software installed can view the shadow copies available for a shared network folder. Windows Server 2003 supports the following five backup methods:
The System State data contains information that is critical to the proper startup and operation of your Windows Server 2003 computer. The following items are included in the System State data:
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EAN: 2147483647
Pages: 151