Hi @karun.keeriot
Thanks for the detail. @Mildur has already provided some great input on this, so I’d like to take a different approach to looking at this and try to add further value.
Requirement 1 :He needs to have 10yrs of his email data backed . ( Has a similar backup policy on VBR where we have configured backups to happen on last day of the month with a retention policy of 12 restore points)
This sounds like everything needs to be retained for 10 years. Email backup isn’t instantaneous like if it was part of an SMTP relay, so it has to happen on a scheduled frequency. If you only processed emails monthly, you could miss out on a lot of content within that duration.
Requirement 2 : Monthly full backups for 1 Yr ( Yearly Backup policy configured for month of December to archival tier using the proxy appliance from blob storage to archive storage on azure with 10 restore points )
I would tip this on its head and consider the following structure:
Backup Frequency: Daily
Repository Configuration: Snapshot-level retention, this will be similar to image-based backups.
Backup Repository: Object Storage with 1 Year retention
Backup Copy Job: Extended with AWS Glacier / Azure Archive with 10 year retention set to immediate.
This way, you create a backup to your faster and immediately accessible object storage initially. This has the benefits that, if you’re on a metered API, it’s cheaper for access and egress of data typically than archive. As we’re using snapshot-based backups in this scenario, it doesn’t matter what the age of the email is, just when the email was deleted from the M365 mailbox. You could have a 10 year old email that was deleted yesterday, so it will sit within your main object repository for a year.
Then I’d utilise a backup copy job with retention for 10 years, immediately performing backup copies. This gives an immediate benefit of having multiple backup copies, were you to suffer corruption or some other misfortune. But this also means that you can meet your 10 year retention requirement if necessary. There’s some ambiguity on when you said “needs email for 10 years”, whether that’s the age of the email (if so, swap snapshot-based retention for item-level retention), or based on when it was deleted from the mailbox.