Hello sai,
Sounds like you have a few questions here. Let's go through them.
I do recommend that you speak to a CA Business Partner or CA Services though, as you'll get better business use out of the new features and avoid some of the pitfalls of upgrading.
1. What are the pre and Post up gradation Steps.
Start with the ITSM 17.1 Upgrade documentation:
Pre-Planning for an Upgrade - CA Service Management - 17.1 - CA Technologies Documentation
2. What are the common issues faced?
There is no getting around that there is a significant amount of planning that needs to go in to get an upgrade to go smoothly. It is usually cutting corners that causes an issue, such as not checking compatibilities or not scoping the system to handle the new version (it does use more resources). Luckily you're asking some of the right questions here.
In short, check, check and double-check. Make sure that you can upgrade a test environment smoothly as a minimum test. My personal No.1 tip would be to try this out on a virtual system, that you can quickly restore a snapshot to if needed.
3. Can we follow the swing box approach to upgrade directly from r12.7 to r17.1?
Yes.
* You can upgrade SDM 12.7 to 17.1. See here:
Upgrading - CA Service Management - 17.1 - CA Technologies Documentation
* The Swing Box method is documented here:
Use the Swing Box Method to Upgrade to CA SDM 17.1 - CA Service Management - 17.1 - CA Technologies Documentation
4. As per supportibility matrix mssql 2008 is not supported so what to do and how to upgrade please provide me guidelines step by step
Upgrade the database to a version compatible with ITSM 17.1 first, and then upgrade the ITSM application from SDM 12.7 to ITSM 17.1. Remember, you don't need SDM 12.7 to be running for the upgrade to work (in fact, it can't), so this is why the database can be upgraded first.
* Upgrade the database.
* Upgrade SDM via the Swing Box method.
Current database versions are here:
Supportability Matrix - CA Service Management - 17.1 - CA Technologies Documentation
Thanks, Kyle_R.