Back in May Microsoft announced the general availability of Recovery Services Vaults on the ARM Platform that provided a single vault for Backup and Site Recovery services to be managed. Around the same time Microsoft announced an upgrade path to allow for the seamless upgrade from classic Backup Vault to ARM Recovery Services Vault.
Today Microsoft have announced that all classic Backup Vaults will now automatically be upgraded to ARM Recovery Services vaults starting from October 31. This will incur minimal downtime with the upgrade process taking roughly 20 minutes, and will enable new features and capabilities available in the ARM vaults.
If you wish to upgrade the vault before this date, you can perform the upgrade. This requires that you have your subscription whitelisted and enabled for the upgrade process.
This can be achieved by following the link to register for the upgrade process https://azure.microsoft.com/en-au/blog/upgrade-classic-backup-and-siterecovery-vault-to-arm-recovery-services-vault/ , alternatively you can raise a support ticket to have the feature enabled for your subscription.
Once the subscription has been whitelisted the steps to upgrade the vault can be followed at this link https://docs.microsoft.com/en-us/azure/backup/backup-azure-upgrade-backup-to-recovery-services.
Currently this is not available for CSP based subscriptions, and it is reported that this will be coming in following updates.