1. Server Types Different servers do different jobs. Proxy Servers Mail Servers Web Servers Applications Servers FTP Servers Telnet Servers List Servers Video/Image Servers Virtual Servers

2. Virtual Server A server, usually a Web Server, that shares computer resources with other virtual servers. A virtual server – that is, the entire computer is not dedicated to running server software. Virtual Web Servers provide low-cost web hosting services. (Dozens of virtual servers can co-reside on the same computer instead of requiring a separate computer for each server.)

3. Virtual Server In most cases, performance is not affected and each web site behaves as if it is being served by a dedicated server. However, if too many virtual servers reside on the same computer, or if one virtual server starts hogging resources, Web pages will be delivered more slowly.

4. Virtualization Turns a single computing platform into two or more virtual computing platforms. –Various forms of virtualization: –Server virtualization (e.g. 2008s, Linux) –Workstation or PC virtualization (e.g. XP, Vista, Unix) –Application virtualization –Hardware or CPU virtualization –Network virtualization

5. Advantages of Virtual Servers Ability to Consolidate Servers (Reduce the number of servers) Uses Hardware Effectively (Take advantages of the full power of hardware) Enable Hardware Independence (Disaster recovery easier) Abilities to Use Multiple OS (2003, 2008, Linux, Unix) Provides Effective Development Environment (Development/Testing and Production)

6. Advantages of Virtual Servers Offers Business Advantages Lower hardware costs Lower utility bills (A/C, heating, costs for running computers) Reduced staff costs Reduced costs for space (Staff, Computer Room, etc) Reduced software development costs Reduced software implementation costs Reduced costs for implementing systems on new hardware More disaster recovery options

7. Dis-Advantages of Virtual Servers Server hardware can be a single point of failure Plan to build in hardware fault tolerance and disaster recovery to reduce the impact of hardware failure Purchase server hardware that contains redundant power supply, CPU, memory, NICs, RAID 1 or 5 disk storage fault tolerance. A backup server computer on hand Set backup computer with virtual machines to match those on the primary computer

8. Dis-Advantages of Virtual Servers Place the backup computer in a different location from the primary server Backup all of the virtual machines on a single computer can be a much slower process than backing up a single computer with a single OS Backing up virtual machines can stress network, CPU, and memory on a single computer (Employ incremental backups or purchase software designed to expedite backups on virtual machines)