You can use different protection methods to meet your specific requirements.
IntelliSnap Plus Backup Copy
When IntelliSnap is used, a hardware snapshot is created on the storage array as soon as the VMware snapshot is completed, then the VMware snapshot is removed immediately. This approach minimizes the size of the redo log and shortens the reconciliation process, to reduce the impact on the virtual machine being backed up and lessen the storage requirement for the temporary file. The secondary backup copy is then performed from the hardware snapshot, outside the production environment.
Large, critical, and high transaction virtual machines can be excluded from streaming backups and protected using IntelliSnap snapshots. Snapshots support application consistent backups for applications such as Oracle, SQL Server, SharePoint, and Exchange. Hardware snapshots provide multiple persistent recovery points a day for critical VMs, including full VM recovery as well as granular file and folder level recovery, while minimizing the load on production VMs and infrastructure.
In the event of corruption of a full datastore where the underlying storage volume is intact, IntelliSnap enables a full volume revert at the hardware level, enabling all the VMs in the datastore to be recovered at the same time, leading to lower down time.
Multiple readers can be configured to perform simultaneous quiescing of multiple VMs for faster creation or deletion of software snapshots, reducing the overall IntelliSnap job time.
The redo log time for large VMs is minimized, to enable larger datastores and VMs to be protected.
A snapshot (Snap Copy) can be used by an ESX proxy as the source for secondary VADP backups, offloading the backup load for the largest VMs to minimize the impact on production systems.
Benefits
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Low impact on productions systems
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Multiple recovery points per day
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Fast recovery copy
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Reduces the backup workload by using a proxy server to create the daily backup copy.
Considerations
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An ESX proxy is needed to mount a hardware snapshot for Backup Copy operations.
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Additional storage required for snapshot reserve.
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Possible impact on other production systems using same storage.
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Array overhead during snapshot mount operations.
Traditional VADP Protection
Backups of virtual machines begin by quiescing the virtual machine and taking a VMware software snapshot. While the backup is in progress the virtual machine disk (VMDK) is frozen and changes are written to a temporary file (redo log). Once the backup completes, the VMware snapshot is removed and the virtual machine disk is updated with changes from the redo log (reconciled). For high transaction VMs the redo log can grow significantly if the backup takes a long time to complete, approaching the size of the entire VMDK for the source virtual machine. For other VMs, the changes recorded in the redo log are minimal.
VADP provides protection through an initial full backup supplemented by daily incremental backups and a periodic synthetic full backup to provide a single daily recovery point. This approach can include the following elements:
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VMware‘s Changed Block Tracking (CBT) feature identifies changed blocks for incremental backups.
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A synthetic full backup merges incremental changes from backup media to create a complete point-in-time VM backup without accessing the production VM.
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A secondary copy of a virtual machine can be updated regularly using the DASH Copy feature with deduplication. Only changed data is written to the secondary copy. DASH Copy creates a new full backup by updating reference counters on deduplicated blocks that exist on disk. DASH Copy can be run on a frequency dictated by your backup retention policy, ensuring that old data blocks that are no longer needed are deleted from the system (known as data aging).
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Advanced transport modes for VMs (SAN or HotAdd) minimize the impact of backup operations on local area networks (LANs).
This approach meets short term and long term retention needs with minimal impact on VMs, and can be used when a limited number of ESX proxies (required for IntelliSnap Backups) are available.
Benefits
- It is possible to recover a full VM or any individual file from an incremental point in time backup (primary copy or any secondary copies). There is no need to consolidate daily backups into a synthesized full backup.
Considerations
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For high transaction VMs, this approach may not be optimal, because high change rates in VMs require a long reconciliation process.
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For high transaction VMs, incremental changes using CBT can take almost as long as a full backup because changes are written across the disk.
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If hardware snapshots are required for some virtual machines, those can be configured in a separate backup set.
In-Guest Agents
In some cases, high transaction virtual machines can be protected by installing an application or file system agent in the guest (source VM). This approach is useful when storage is presented directly to a virtual machine including RDMs, direct iSCSI, or NFS, or when the VM has a large database or large number of files. This can also be used to address VMs that do not tolerate a VMware snapshot no matter how brief the duration.