Can we update SLA without impact on OLD issues

[Madhu Reddy]

We have a new requirement to Update SLA's.

When I tried to update SLA in my test instance all my OLD existing issues got updated with the New SLA timings. 

Can we update SLA's without impact on the existing issues ? Please suggest.

Thanks in Advance. 

[Daniel Ebers]

Hi Madhu,

how are "OLD" issues defined in your context?

For updating SLA the following applies:

If you edit an existing SLA, Jira Service Management will re-index all the existing issues in the project. All the SLA data for elapsed time will be recalculated to measure against the new metrics. The SLA status is only recalculated for open issues, not for resolved issues. 
For example, when the goal for Blocker issues changes from 6 hours to 4 hours, all the closed issues are still considered having met the goal as long as they were resolved in less than 6 hours. This ensures that your reports on closed issues remain accurate for the issues' lifecycle.

https://confluence.atlassian.com/servicemanagementserver/setting-up-slas-939926373.html

So, if I understand you right - this works differently in your instance? What are you observing exactly?

Regards,
Daniel