There are three main ways to quickly and efficiently deploy multiple, identical systems with identical hardware and software configurations - Manually build them, script part or all of the install and configuration, or hard drive imaging. Here are the advantages and disadvantages of each.

Build by hand

This method gives you complete control of the process but takes the longest and affords many opportunities for user error -- especially in configuration. Also, unless you're diligent, the first system might not be set up exactly the same as subsequent systems.



Advantages

- Total control of process from start to finish

Disadvantages

- Most time consuming

- Greatest chance for configuration error

- Greatest chance for inconsistencies in software from one system to another

Scripted installs



This approach allows you to set many configuration parameters up front, which saves a considerable amount of time, but since you must have some prior knowledge of an applicable scripting language or learn it as you go, this method can take considerable time.

Advantages

- Less hands-on -- Start it up and walk away

- Less time-consuming overall for a moderate number of systems than building by hand

Disadvantages

- Portability of configuration scripts from one deployment project to the next is variable

- Initial time investment in script development can be considerable

- Scripted solutions don't always do what you want them to do out of the box

- Requires knowledge of scripting languages for supplemental configurations (i.e. Perl, Shell)

Hard drive imaging



Hard drive imaging allows you to create a model system that you want your other systems to mirror. This method requires special software to clone the contents of the entire hard disk or disks to any number of target systems.



This method is highly scalable. You can clone one system to any number of systems simultaneously over a local network connection. It's also generally very fast -- especially if the cloning software you choose has intimate knowledge of the file systems used on the model system, such that it can distinguish between data and free space.



One problem with hard drive imaging arises when you use a large hard disk and a file system with which the cloning software is unfamiliar. In this situation, the software will copy the source hard disk block by block, making no distinction between free space and data. With large modern hard disks this can take tens of hours to complete, and when an error is encountered, you must start the process again from the beginning.

Advantages

- Creates exact duplicate of contents of one hard disk/volume to another

- Delivers hard drive images over the network to one or many systems simultaneously

- Resizes individual partitions of many file systems of which the disk cloning software (i.e. Ghost) has intimate knowledge

Disadvantages

- Lack of intimate knowledge of file systems forces block by block copy of source hard disk into image, which can take a long time to complete for large disks

- Offers little detection or recovery from errors during image generation and deployment

- The best hard disk imagers are commercial and expensive

» posted by jnaze

ITworld.com

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