Why do we need Azure backup for our VMs (disks) on azure, when azure storage account provides different replication options like LRS, ZRS, GRS, RA-GRS.
All the data is already replicate in different region (in case of GRS), what advantes I will get out of Azure Backup.
All the data is already replicate in different region (in case of GRS), what advantes I will get out of Azure Backup.
Replication is not backup!
It is true that when you opt for GRS replication, 6 copies of your data is maintained (3 in primary and 3 in secondary) but when you delete the data from primary, data from secondary is automatically deleted.
UPDATE
You mean, if any data is deleted/corrupted due to some error/bug, can be reproduced from backup and it is not possible in case of storage replication.
You're absolutely correct!
But Microsoft sells "Azure backup and Site recovery" as a BCDR strategy. In context of any disaster, why not just rely on Storage replication. Any advantages of Azure backup/site recovery?
I have not used Azure backup so let me answer it from Storage Replication point of view. To put things simply, "In context of Azure, a disaster is not a disaster unless Microsoft thinks it is a disaster". Till the time that happens, you don't get access to secondary assuming you have opted for GRS replication (with RA-GRS, you obviously have an option to read the data from secondary at all times).
Furthermore if you choose LRS or Premium LRS replication and there's indeed a disaster in one data center, all of your data will be lost. With Azure Backup, you at least have a copy of your data lying somewhere safe and you could recreate your environment based on that backup.