About Data Protection and Snapshots

This chapter provides an overview of data protection, server-level backups, and data recovery. It also describes how Core integrates with the snapshot capabilities of storage arrays, enabling you to configure application-consistent snapshots through the Core Management Console.

Data protection can mean different things to different people. In the context of storage, using very simplistic terms, it is about ensuring your data is safe such that if the original data is lost in some way, another copy that you have backed up on alternative storage can be restored. This chapter aims to provide you with some general information about how the product can integrate with existing data protection strategies that you may have in place, but also offers additional tools and capabilities that could improve or even replace some of the existing approaches you may have.

The product provides the ability to back up data using policies that have a VM-aware capability making it even easier to keep to best practices when protecting your data. This feature is discussed further in the section called Server-level backups. But to begin with, the next sections cover the subject of snapshots, which form the basis of a data protection strategy.

The system provides tools to preserve or enhance your existing data protection strategies. If you are currently using host-based backup agents or host-based consolidated backups at the branch, you can continue to do so within the product context. However, Core also enables the following strategies.

The product family continuously synchronizes the data created at the branch with LUNs hosted in the data center. As a result, you can use the storage array at the data center to take snapshots of the LUN and thereby avoid unnecessary data transfers across the WAN. These snapshots can be protected either through the storage array replication software or by mounting the snapshot into a backup server.

Such backups are only crash consistent because the storage array at the data center does not instruct the applications running on the branch server to quiesce their I/Os and flush their buffers before taking the snapshot. As a result, such a snapshot might not contain all the data written by the branch server up to the time of the snapshot.

Release 5.1 and later provide support for data protection of VMware virtual machines (VMs) that include Edge Local LUNs as part of the VM. Since data written to local LUNs is not synchronized back to the data center, a different approach is needed in this scenario. Therefore, to protect these types of VM, the product server-level backup feature is able to back up the VM that is resident on a projected LUN but will automatically exclude any local LUN that the VM is configured to use.

Prior to release 5.1 in this scenario, the VM itself would be excluded from server-level backups as well as the Edge Local LUN.

This option uses the product Microsoft VSS integration in conjunction with Core storage array snapshot support. You can trigger VSS snapshots on the data drive of your branch Windows servers at the branch, and the Edge ensures that all data is flushed to the data center LUN and triggers application-consistent snapshots on the data center storage array.

As a result, backups are application consistent because the Microsoft VSS infrastructure has informed the applications to quiesce their I/Os before taking the snapshot.

This option relieves the backup load on virtual servers, prevents the unnecessary transfer of backup data across the WAN, produces application-consistent backups, and backs up multiple virtual servers simultaneously over VMFS or NTFS.

In this option, the ESX server, and subsequently the Core, takes the snapshot, which is stored on a separately configured proxy server. The ESX server flushes the virtual machine buffers to the data stores and the Edge appliance flushes the data to the data center LUN(s), resulting in application-consistent snapshots on the data center storage array.