Daggupati,

Rollbacks to a previous version is not possible. Not even on the procudtion day, not even after 1 seconds after the upgrade.

Thats why people first test thier upgrade activities in thier sub production instaces first, then they upgrade the production instaces.

About your question on Backup: A backup is a snapahot of your entire instance at a particular point of time, which contains your tables + configurations + every other entity. ServiceNow maintains seven daily and three weekly backups on disk. Daily backups are preserved for one week. Weekly backups are preserved for one month. The backup will include everything in the instance at the time the backup is completed.

Kindly note that restoring from backup is a last resort. There is always the potential for data loss because anything saved after the backup is lost. Also, while the restoration process is running, the instance is unavailable, furthermore it is not possible to have an estimate time of completion of the restore.

Avoid restoring a production instance from backup, when possible, due to downtime and data loss. Restoring a production instance from backup is a final option when a problem cannot be solved using other methods.

Hope this helps,

Aman Gurram