Backup storage type#

VM Backup is a long-term storage of VM snapshots in reliable and cost-effective storage for further data recovery from stored Restore Points.

Despite the fact that Hystax Acura Disaster Recovery already has sophisticated retention policies available, long-term storage with many Restore Points might be very expensive. This expensiveness comes from the type of storage used for Disaster Recovery purposes. For Disaster Recovery case, which requires minimal RTO, Hystax Acura stores data in cloud-native block devices (e.g. EBS Volumes, Cinder Volumes and their snapshots), which are:

quite expensive
charged for provisioned size
cloud snapshots might also be charged by provisioned size of the source volume

For higher storage effectiveness in case if Hystax Acura is used for VM Backup, it has alternative storage scheme. In this alternative, Hystax Acura stores replicated data into an object or a file storage. To implement this storage method select an S3-compatible, Unix or Windows share storage.

You can select an object or a file storage for replication on cloud connection form:

pp_s3_cloud

Select 'S3-compatible storage', 'Unix share (NFS)' or 'Windows share (SMB/CIFS)' as 'Replication storage type' and enter storage connection credentials to keep data instead of cloud-native block storage.

All other functionality of replication/recovery is similar to the Disaster Recovery case.

Object storage#

In case of object storage ('S3-compatible storage') greater efficiency is achieved through deduplication in the storage system, the ability to store a longer history of recovery points. However, the drawback of storing replicated data in object storage is longer RTO. When Hystax Acura recovers VM from object storage, it adds disk render operation, which copies data from object storage to block devices, to usual operations performed during recovery. This operations linearly depends on data size in Restore Point and network bandwidth between storage, Hystax Acura Controller and target cloud.

For each Restore Point, Hystax Acura creates the following objects in the object storage:

data objects: at least one per volume of replicated machine. Data object for disk can be splitted to objects by 50Gb
Restore Point metadata object: sqlite database which holds block mapping

The described storage scheme has provided the following:

storage is charged by consumed space for replicated data
object storage is less expensive than block storage