1. MAINTAINING SERVER AVAILIBILITY
CHAPTER 6
MAINTAINING SERVER AVAILIBILITY

2. Using performance console
You may use performance control to monitor your system .
It provides a lot of information on the hardware components installed in your computer, services as well as your network performance.
Information will be displayed in the form of graphs & you may choose as many counters as you may want to be monitored.
Start – control panel – administrative tool – performance logs & alerts / system monitor
The counters you selected will appear as lines in the graph & as entries in the legend
at the bottom of the window.

3. Using performance console
Although you may add a lot of counters, its advisable to keep it small numbers to avoid over- crowding the graph.
Tips to consider when selecting counters;
limit the number of counters – to many counters will make the graph difficult to understand.
Modify the counter display properties – depending on the size & capabilities of your monitor, you may adjust the lines color & widths for better monitoring
Choose counters with comparable values – same counters are not suitable to be displayed together due to disparate values ( value under 20 & value above 100)
Adjust the vertical scale – reducing the maximum value of the scale will make it easier to read.

4. Using performance console
Network Traffic Monitoring
System monitor also includes counters for many network statistics.
You may use these counters to monitor the network traffic the computer is sending & receiving in variety of ways. Some of the counters are;
Network interface
IPv4
ICMP
TCPv4
UDPv4

5. Monitoring Network Server Services
Network services are the applications that always run in the background processing / receiving client requests.
Keeping services running
Its common for network administrator to find the DNS name resolution / DHCP address is failing simply because the service isn’t running.
Reasons contributing to this;
Service might not have started when the server got restarted the last time
Another administrator might have stopped it for some reason & fail to start it again
Conditions of the server might have caused the service to stop.

6. Monitoring Network Server Services
Monitoring DHCP
By default DHCP server leases out IP to clients for 8 days at a time.
If all your computers obtained IP from your DHCP server & then the server fails, your computer may still use the same IP until it expires after 8 days.
Monitoring DNS
A malfunctioning DNS server gives bigger impact & below are the effects;
Internet clients cannot access internet servers
Internet users cannot access your company’s www servers
Internet directed to your domain bounces
Active directory service clients cannot locate a domain
controller & therefore cannot log on.

7. Locating system bottlenecks
When there is a performance problem which is not caused by service failure, then the most common causes is bottleneck somewhere in the path of network.
To locate bottleneck is a complicated task & you must examine the 4 main subsystems of a computer
Monitoring processor performance – if processor time counter reaches 100% then its an indication of bottleneck
Monitoring memory performance – use counters in memory performance to see Available Mbytes
Monitoring storage subsystem performance – adding more harddrives as separate entity is not advisable, split your data
Monitoring network performance – increase the network speed / install additional network adapters in the server
& redistribute the network

8. Understanding network backups
Backup hardware
Magnetic tape
High capacities, low media costs & reliable long term storage
Capacity between 50GB – 200GB
Backup software
An application that enables you to select the files you want to back up.
The difference between various backup software products is the extra features that the application includes.

9. Creating a backup plan
After choosing the software & hardware needed for the backup, next create a plan that contains these elements;
What data will be backed up
When backups will occur
Which tapes to use & when
Sometimes its not practical to backup all the data in the computer due to these reasons;
There is to much data to back up
There is not enough time to do back up
There is too much of redundant data

10. Backup job types 3 most common types are as below;
Full backup – copies all the selected files to the backup medium & resets the archive bits for all the copied files
Incremental backup – copies only the selected files that have archive bits & then resets those archive bits
Differential backup – copies only the selected files that have archive bits without resetting those archive bits.

11. Performing restores
A good backup software product gives you a lot of flexibility in restoring & some of the basic options are;
File selection – should be able to select any combination of files, folders or drives on any type.
Restore location – you should be able to restore your selected files to the original locations automatically.
Overwrite options – when restoring files to their original location, you should be able to specify the criteria for overwriting existing files with the same name.