Added operational guidance on database backups and resetting users in SMI for the pooling.

docs/services/subject-moderation-interface.md

@@ -130,6 +130,37 @@ The flow of applicant data to/from the SMI and other services is summarised by t
 
 Further information is available in the [Operational Documentation for the Undergraduate Admissions process](https://gitlab.developers.cam.ac.uk/uis/devops/uga/operational-documentation).
 
+#### Preparation tasks for new cycle
+
+##### Backups
+
+Backups are run nightly, and a week's worth of the automated backups are stored. On-demand backups are stored indefinitely until deleted. It is recommended to take an on-demand backup before performing cycle changeover actions.
+###### Perform manual database backup
+
+1. Go to Google Cloud Console, and select the environment of "UG Admissions" you're looking for.
+1. Navigate to the SQL instance for that environment.
+1. Select "Backups" > "Create backup".
+1. Give the backup a meaningful name, e.g. "Before updating SMI users for 2022 summer pool".
+
+Taking a backup usually takes a couple of minutes. Restoring a database instance from a backup can take up to 20 minutes to complete, in practice.
+##### Resetting user access
+
+Between cycles, we need to clear down the users setup for just that cycle. This enables staff to invite only those now relevant to the role for the next cycle.
+
+This involves deleting the following associations of users to the following auth groups:
+
+1. "Admissions Tutors" group
+1. "College Admissions Administrators" group
+1. "Directors of Studies" group
+1. "Interviewers" group
+1. "Subject Convenors" group
+1. All "[College] Affiliated Users" groups
+1. All "[Subject]  conveners" groups
+
+This can be done group-by-group manually through the SMI admin interface by DevOps.
+
+In particular we do not clear down members of the "Central Admissions Officers", so CAO staff can begin re-adding key users in each college. As we don't erase users, and DevOps team members are marked as superusers, these also survive the yearly reset process.
+
 ## Service Management and tech lead
 
 The **service owner** for the SMI is Helen Reed.