Azure VM Backup Considerations (part 1)

 


To read part 2 please click here


Application Backup

SAP applications hosted by VMs can be easily backed up using Azure backup whose agents supports throttling utilized during backups and restores. Azure backup completes a  backup by using following ways for Azure VMs:
  • Azure backup always start the backup job according to the backup schedule you specify for the Azure VMs selected for backups.
  • A backup extension is installed on the VM if the VM is running during the first backup.
  • After the backup takes the snapshot, it transfers the data to the vault.
  • When the data transfer is complete, the snapshot is removed, and a recovery point is created. 

Database Backup

Azure VM-based DBMS' backup can be performed by using DBMS-specific methods which should also facilitate the ability to restore it to any point in time. To achieve this capability two types of backups must be performed:
  1. Database full & differential backups
  2. Transaction log backups

Besides the full database backups performed at the database level, you can also perform backups with storage snapshots. While storage snapshots can accelerate the recovery by quickly providing a roll-forward image of the database, the transaction log backups too remain important to restore the database to a certain point in time or to empty the logs from already committed transactions.

File-snapshot backups are very useful for SAP administrative tasks, like applying SAP support packs. But, the best practice to backup your SAP applications before applying any kind of support packs and upgrades or performing any other major data operations such as archiving.

SAP HANA Backup

The following two methods can be used to backup SAP HANA on Azure VMs:
  1. HANA backup to the file system in an Azure Linux VM
  2. HANA backup based on storage snapshots using either the Azure storage blob snapshot feature manually or Azure VM level backup

The choice between these two methods is not provided by SAP , but pros and cons are offered so that anybody can determine which to use depending on the situation as well as available storage technology.

File system consistency is available while using the SAP HANA snapshot feature, and if there is only single virtual disk is involved. But, this topic becomes more challenging when a single file system spans multiple disks/volumes. 

If there is an XFS file system spanning four Azure virtual disks, the following steps provide a consistent snapshot that represents the HANA data area:

  • HANA snapshot prepare
  • Freeze the file system (for example. use xfs_freeze)
  • Create all necessary blob snapshots on Azure
  • Unfreeze the file system
  • Confirm the HANA snapshot

It is recommended to use the procedure above in all cases to be on the safe side, no matter wḥich file system.



To read part 2 please click here


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