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Last updated: Apr 18, 2024

Snapshot Vs. Backup: Understanding the Difference and Best Practices

VM backup vs. snapshot, is this the same thing? Well, no, but both are done for the same purpose – to have a source to fall back on in disaster times. Understanding the difference between these two strategies is actually necessary for IT experts.

Snapshot Overview

A snapshot is a recorded image of a virtual machine at a particular point. The snapshot captures the complete state of a virtual machine, including all files and data on the machine; you can record a snapshot while a VM is running or suspended. Snapshots act as “Windows Restore Point” or “Previous Versions,” allowing you to roll back a VM to an old state (to the state the VM was when the snapshot was taken).

What is a Snapshot and its Purpose?

Snapshots can also be called “checkpoints” in Hyper-V environments. As a point-in-time image file, a snapshot may capture the complete version of running tasks as at when it was triggered (this is when a snapshot is taken without putting the VM to rest or suspending running tasks). It is important to note that a snapshot stores the memory, disk, and settings data of a VM – including the configuration data. 

Apparently, the purpose of taking snapshots is to have a rollback version of your VM. If you make advanced changes to a VM and end messing up more settings or files, you can roll back to a snapshot and regain your VM’s previous settings and files; it’s some kind of backup, no doubt.

How do snapshots function?

The first snapshot records wholesome data; this means it records everything about the VM. When you take subsequent snapshots, only changes to the previously recorded data will be recognized and captured. A snapshot file contains two sub-files: a .vmdk file and a delta.vmdk file.

Changes to a snapshot file are written to newly created delta disk files stored in the same folder as the base disk. So, while the first snapshot may take a little longer to record, subsequent ones record much faster.

.vmdk file: Refers to a virtual disk file containing raw data from the base disk. 

delta. vmdk file: More like an incremental backup file that captures all changes between the current state of a VM and the last recorded snapshot.

Types of Snapshots

Actually, there are two types of VM snapshots, however, system admins figured out there are strategies that could be classified as “types” of snapshots.

1. Copy-on-Write Snapshot (CoW)

A CoW snapshot is a type that captures only the metadata of new data blocks from the last time a snapshot was taken. It captures data changes and creates a new “snapshot” copy for the new files/data. Since CoW doesn’t copy the entire metadata (but only that of the newly written data), it is very fast and space-efficient – utilizes three I/O operations for each write: one read and two writes.  

2. Redirect-on-Write (RoW)

RoW is a type of snapshot that creates a new copy of the new data from the last time a snapshot is taken – and saves it on the snapshot storage. This snapshot type utilizes more resources because each new data block generates a single write IO. Redirect-on-Write snapshots redirect write operations to a new storage, while the original data remains intact for as long as needed. 

3. Continuous Data Protection

This type of snapshot is recorded in real-time – every time a change is made. A continuous data protection snapshot updates the original snapshot copy every time new data is written. It is best for tracking real-time modifications by saving every new version of data. Well, as you may expect, this causes a high impact on the network performance and bandwidth.  

4. Clone/Mirroring

A clone/mirror snapshot is not basically a type of snapshot, instead, just as the name implies, this refers to replicating an entire virtual machine volume to create an identical copy of the storage and its contained data. 

This replicated copy is usually saved to an external storage, so, regardless of the disaster that befalls the VM’s host system storage, you can still have access to your VM’s files and configuration. This literally means backing up your VM to external storage. 

Of course, this process is slow because it copies everything each time it runs – unlike snapshot techniques that would freshly generated data, and it’s bulky in size.

Pros and cons of snapshots

Pros of Snapshots

  • Allows for faster rollback to a previous version of a VM – much faster than backups. 
  • You can easily create snapshots than backups
  • Snapshots have less bulky size than backups
  • You don’t need a third-party solution to backup or restore snapshots

Cons of Snapshots

  • If the VM disk file is affected, the snapshot(s) are lost 
  • The more snapshots you take, the more space it occurs
  • You can’t recover files individually, you must recover everything at a go

Backup Essentials

Data loss scenarios cannot be completely avoided no matter how careful you are or the strategies you apply. This is why, data backup is advised for everyone who deals with data – at any level. The best way to keep your data safe is by backing them up on an external device (not the same device where the data is been written to, primarily).

Understanding backups and their role

In simple terms, a backup is a duplicate copy of important data or an entire hard drive. Backups are created to have a fallback place in times of data loss. Creating backups has always been the best resort to being safe in severe data loss scenarios. Just as there are different types of snapshots, there are equally different types of backups.

Also, backups can be made using built-in tools or third-party applications that support such. Interestingly, there are multiple data backup utilities that exist, both free and paid apps. The backup and recovery options you will have access to depend on the backup application you decide to go with. 

Note: Backups must be saved to an external disk, not the same primary storage where your files are saved. The reason is simple, if you save backup files on the same drive as the main data, when the drive fails, both the backup and main data would be inaccessible. It is even more advisable to save your backup files on different external drives or cloud platforms.

How Backups Operate

Backup mechanics involve a series of operations designed to safeguard data by duplicating it from a primary location to a secondary one, ensuring that information remains available even if the original data is lost or compromised. Let's delve deeper into how backups operate and explore their benefits and drawbacks.

  • Full Backup: Captures every file in the system or within the selected dataset. This is the baseline for any backup strategy.
  • Incremental Backup: Records only the changes made since the last backup (whether the last backup was full or incremental). This method saves time and storage but can lead to longer recovery times, as each incremental backup must be restored in sequence following the full backup.
  • Differential Backup: Captures all changes made since the last full backup. Each differential backup grows larger over time but simplifies recovery because only the last full backup and the latest differential backup are needed.
  • Continuous Data Protection (CDP): Instead of scheduled backups, CDP continuously (or very frequently) backs up data changes almost in real-time, providing a highly granular restore point.
  • Mirror Backup: Creates an exact replica of the source data. This can be particularly useful for critical systems that require immediate recovery with minimal data loss.

Benefits of Backups

  • Data Protection: Protects against data loss due to hardware failures, human errors, software corruption, or cyber attacks.
  • Disaster Recovery: Facilitates the restoration of data in the event of a disaster, ensuring business continuity.
  • Compliance: Helps organizations comply with legal and regulatory requirements for data retention and protection.
  • Version Control: Enables the recovery of earlier versions of data, which can be crucial for addressing accidental deletions or changes.

Drawbacks of Backups

  • Cost: Storage costs for maintaining multiple backups can be significant, especially with full or differential backup strategies.
  • Complexity: Managing backup schedules, storage media, and restore processes can be complex, particularly for larger organizations with vast amounts of data.
  • Recovery Time: Depending on the backup method used, recovery can be time-consuming. Incremental backups, in particular, may require more time as each segment of the backup needs to be restored in order.
  • Bandwidth Usage: Backups, especially cloud-based backups, can consume significant bandwidth, potentially impacting network performance.
  • Security Risks: Stored backups can also be targets for theft or cyberattacks, necessitating robust security measures to protect backup data.

Comparing Snapshots and Backups

The two may look similar, but they are definitely not the same. Albeit, they seem to serve the same purpose. Snapshots are not as reliable as backups because they are connected to a VM and can go missing if the VM’s file is tampered with. On the other hand, a backup can contain the entire tire of multiple VMs, provided the VM files are stored on the same hard drive. 

But, snapshots can be easily restored compared with backups. To restore a snapshot, you just have to perform a few clicks but to restore a backup, you may require some time to get the backup file from where it is stored and load it to the affected storage. Well, the required time could be as short as 3 minutes or as long as 1 hour for a backup file to be successfully restored. But you can restore snapshots in less than a minute. 

Of course, you can have both snapshots and backups and while you can use snapshots as backups (to an extent), it is not advisable that you view it in that manner. Take snapshots of your VM, but ensure to make offsite backups too. Snapshots cannot replace backups, but backups can replace backups; however, snapshots can come in handy if no prior backup has been made.

Features

Snapshot

Backup

Data Location

Saved in the same location with the VM files. 

Can be stored offsite – in an entirely local or offline storage

Restoration

The VM files must not be corrupted for the restoration to run successfully

Doesn’t depend on the VM files or storage. Data can be restored even when the VM’s primary disk is tampered with.

Recovery Time

Faster

Relatively slower depending on the data size and backup location 

Retention Time

Limited to a length of time

For as long as the storage device is still accessible

Summary of Snapshots vs. Backups and Disaster Recovery Strategies

Snapshots and backups are both crucial in data management and disaster recovery strategies, but they serve different purposes and have distinct characteristics. Here’s a summary that differentiates snapshots from backups, along with an overview of disaster recovery strategies.

Snapshots vs. Backups

Snapshots:

  • Nature: A snapshot is an image of a system at a particular point in time, capturing the state and data of a system but not necessarily all the data itself. Snapshots are often used with virtual machines, storage systems, or databases.
  • Storage: Typically stored on the same system or storage array, making them quick to create and restore.
  • Use Cases: Ideal for short-term changes or quick rollbacks, such as during updates or patches.
  • Limitations: Since snapshots often rely on the original data location, they can be vulnerable if the primary data source fails or is corrupted.

Backups:

  • Nature: Backups involve copying data to a secondary location, which can be onsite or offsite. They provide a comprehensive record of data as it existed at the time of the backup.
  • Storage: Usually stored separately from the primary data, either on physical media, in a dedicated backup system, or in the cloud.
  • Use Cases: Essential for disaster recovery, long-term data retention, and compliance with data preservation standards.
  • Strengths: Protects against a wider range of data loss scenarios, including total system failures, disasters, and data corruption.

Disaster Recovery Strategies

Disaster recovery involves planned methods to restore access to software, data, and hardware necessary to resume critical operations after a disaster. Key strategies include:

  1. 1. Data Redundancy: Keeping multiple copies of data in different physical locations to safeguard against physical disasters.

  2. 2. RTO and RPO Goals:

    • Recovery Time Objective (RTO): The maximum acceptable time that a system or network can be down after a disaster.
    • Recovery Point Objective (RPO): The maximum acceptable amount of data loss measured in time.
  3. 3. Tiered Backup Strategy: Using a combination of full, differential, and incremental backups to balance storage efficiency, recovery speed, and data availability.

  4. 4. Offsite Storage: Keeping backups in a location separate from the main production site to protect against local disasters.

  5. 5. High Availability Systems: Designing systems to be resilient and minimize downtime with technologies such as failover clustering, load balancing, and redundant hardware.

  6. 6. Regular Testing: Routinely testing disaster recovery procedures to ensure they work effectively and meet organizational objectives.

  7. 7. Cloud-Based Disaster Recovery (DRaaS): Utilizing cloud services for disaster recovery, which can provide scalable, flexible, and cost-effective solutions for data backup, storage, and recovery.

VM Snapshot vs Backup

Snapshot Insights

VM snapshots capture the state of a virtual machine at a specific point in time. This includes the VM's system files, settings, installed applications, and sometimes the current state of active processes. Snapshots are incredibly useful for short-term saves during system updates or software installations, where quick rollbacks might be necessary if something goes wrong.

Understanding snapshots and their applications

Snapshots are not complete copies of the VM's data stored on disk but rather a point-in-time representation of the VM. They work by keeping track of changes made to the VM’s original state since the snapshot was taken. When a snapshot is created, it effectively freezes the files at that moment and any new changes are written to a different file. This mechanism allows for rapid capture and restoration of system states with minimal storage requirements.

Applications of snapshots include:

  • Development and Testing: Developers use snapshots to save and restore states of their virtual environments rapidly during testing phases, allowing for quick reverts to baseline states between tests.
  • System Updates: Before a system update or software installation, snapshots can protect against potential disruptions by providing a rollback point if the update fails or causes issues.
  • Forensic Analysis: In security incidents, snapshots can be taken to preserve a compromised system's state at a specific time for later forensic analysis without disrupting continuity of operations.

While snapshots are invaluable for these uses, they should not be confused with backups. Snapshots depend on the primary data storage and don't suffice for complete data recovery in case of hardware failure. For comprehensive data protection, regular backups are recommended alongside snapshots.

VMware Snapshot vs. Hyper-V Checkpoint

How VMware Snapshot and Hyper-V Checkpoint function

VMware and Hyper-V employ virtualization technologies that allow snapshots and checkpoints, respectively, which are essential tools in VM management. Although they serve similar purposes, their underlying mechanisms have distinct characteristics.

VMware Snapshot: VMware snapshots capture the entire state of the VM at a specific point in time. This includes the VM’s memory, settings, and the state of all the virtual disks. VMware handles snapshots in a multi-layered manner, where each new snapshot creates another delta disk. This means that the original virtual disk remains unchanged, and all changes are stored in these delta disks.

Hyper-V Checkpoint: Previously known as "snapshots" in earlier versions, Hyper-V checkpoints function similarly but are implemented differently. Standard checkpoints capture the state and data at a specific point but are not recommended for production environments because they can affect performance. Hyper-V also offers production checkpoints, which use Volume Shadow Copy Service (VSS) or similar services on Linux, to create a point-in-time image of the VM, which is more suitable for production environments.

Pros and cons of VM snapshots

Snapshots provide a quick way to revert a VM to a previous state, making them valuable for test environments, software updates, or backups before making significant changes. However, their utility comes with limitations.

  • Pros:
    • Quick recovery: Snapshots allow for fast restoration to a previous state, which is crucial during updates or when testing new software.
    • Testing flexibility: They provide a safety net for developers to test applications or updates without permanently affecting the VM.
    • Efficiency: Snapshots are quick to create and do not require immediate additional storage, as they only save changes made from the point of creation.
  • Cons:
    • Performance impact: Prolonged use of snapshots and multiple snapshot layers can degrade VM performance, as the system must read from and write to multiple delta disks.
    • Storage space: Although initially efficient, snapshots can grow significantly over time, leading to storage management challenges.
    • Not a backup solution: Because snapshots rely on the original disk and VM configuration for data integrity, they are vulnerable to data loss if the primary storage fails.

While both VMware snapshots and Hyper-V checkpoints offer significant benefits for managing virtual environments, it's crucial to use them judiciously and in combination with other data protection strategies like regular backups to ensure comprehensive data security and system integrity.

The Importance of Backups in Virtual Environments

Virtual environments have become a staple in enterprise IT infrastructures, hosting everything from critical applications to personal data. While these environments offer flexibility, scalability, and ease of management, they also present unique challenges in data protection. Backups play a pivotal role in safeguarding data within these environments, ensuring that organizations can recover from data loss, corruption, or disasters. Here’s why backups are crucial in virtual settings:

1. Data Integrity and Recovery

  • Rapid Recovery: In virtual environments, the ability to quickly restore operations is crucial, especially for business-critical applications. Backups ensure that data can be restored to a known good state after incidents like data corruption or accidental deletion.
  • Point-in-Time Restoration: Backups allow organizations to revert their systems to specific points in time, which is invaluable when recovering from malware attacks or system failures.

2. Disaster Recovery

  • Geographic Redundancy: Backups can be stored in multiple locations, protecting against site-specific disasters. This geographic redundancy is vital for maintaining operations during regional power outages, natural disasters, or other catastrophic events.
  • Comprehensive Protection: Unlike snapshots, which are often stored within the same storage system, backups can be offloaded to external storage or cloud environments, providing an additional layer of security against simultaneous system failures.

3. Regulatory Compliance and Audits

  • Data Retention: Many industries have strict regulations requiring data to be retainable and retrievable for a certain period. Regular backups ensure compliance with such regulations, helping avoid legal and financial penalties.
  • Audit Trails: Backups can serve as a historical record of data, useful during audits or investigations to understand and verify the sequence of events or changes in data over time.

4. Efficiency and Cost-Effectiveness

  • Resource Optimization: Backups can be automated and managed with minimal manual intervention, allowing IT staff to focus on more strategic tasks rather than routine data protection efforts.
  • Cost Management: Effective backup strategies can minimize the financial impact associated with data loss incidents, which can be substantial in terms of lost productivity, customer trust, and direct remediation costs.

5. Virtual Machine Portability

  • Migration and Testing: Backups can facilitate the migration of virtual machines between hosts or data centers without downtime. They also allow for safe testing of updates or changes in isolated environments before a full-scale rollout.

Best Practices for Backups in Virtual Environments

  • Regularly Scheduled Backups: Implementing a schedule for frequent backups minimizes the risk of significant data loss. The frequency should align with the criticality of the data and business needs.
  • Tiered Backup Strategy: Utilizing a combination of full, differential, and incremental backups can optimize storage use and recovery times.
  • Automated Testing of Backup Integrity: Regularly testing backups to ensure they are complete and the data is recoverable is essential for trust in the disaster recovery process.
  • Secure Backup Storage: Protect backup data with encryption and store it in secure, preferably geographically dispersed locations to mitigate risks of theft, tampering, or destruction.

VM Snapshot vs Backup

VM Snapshot and Backup Overview

Snapshots and backups are two pivotal technologies used in managing data within virtual environments, each playing a unique role in data preservation and recovery.

  • VM Snapshots: Snapshots provide a "picture" of the virtual machine at a specific point in time, capturing the VM's state and data without creating a full copy. They are primarily used for short-term saves and quick recoveries within the virtual environment.
  • VM Backups: Backups involve creating a complete copy of the VM's data at scheduled intervals. These copies are stored independently from the original data sources, providing a robust solution for long-term data retention and disaster recovery.

Differentiating VM Snapshot and Backup

While both snapshots and backups are used for protecting data, their applications in data management differ significantly:

  • Purpose: Snapshots are ideal for immediate, short-term recovery needs, such as pre-update testing. Backups are designed for long-term data protection and recovery from severe incidents like data corruption or hardware failure.
  • Storage Location: Snapshots often reside on the same storage system as the original data, which can pose risks if the storage system fails. Backups are stored separately, often offsite or on a dedicated backup system, enhancing data security.
  • Data Integrity and Completeness: Snapshots can become unreliable over time or if too many are taken due to performance degradation. Backups are more stable and reliable for complete data restoration.

Can VM Snapshots Serve as Backups?

While VM snapshots are useful for quick reversions, they are not a substitute for backups due to:

  • Dependency on Primary Data: Snapshots require the original data to remain intact, as they only record changes from the set point.
  • Vulnerability to Data Loss: If the primary storage fails, snapshots will also be compromised, which is not the case with backups stored separately.

Best Practices for VM Snapshot and Backup Management

  • Regular Scheduling: Automate snapshot and backup schedules to ensure consistent data protection without manual intervention.
  • Lifecycle Management: Regularly review and delete old snapshots to prevent storage overload and maintain system performance. Keep backups as long as required by compliance or business needs.
  • Secure Storage: Use encryption for both snapshots and backups, and ensure that backups are stored in physically secure and geographically diverse locations.

Creating, Restoring, and Deleting VM Snapshots

  • Creating: Snapshots can be created via the virtualization platform’s management interface with a simple click or script command.
  • Restoring: To revert to a snapshot, select it from the snapshot manager and choose the restore option. This will revert the VM to the state it was in at the snapshot's creation.
  • Deleting: Remove old snapshots through the management console to free up resources, which also helps in maintaining optimal performance.

Scheduled Backup and Fast Restore Techniques

  • Incremental Backups: Store only the changes made since the last backup, reducing storage needs and speeding up backup processes.
  • Fast Restoration: Use disk-based backups with high I/O capabilities to speed up restoration times. Virtual machine replication can also be used for almost instant recovery.

3 Simple Steps for VM Backup and Restoration

  • Plan Your Backup Frequency and Scope: Determine how often and what type of backup (full, incremental, differential) is needed based on the criticality of the data.
  • Automate the Backup Process: Use backup software that supports automation to reduce the risk of human error and ensure backups are performed consistently.
  • Test Restorations Regularly: Periodically test the restoration process to ensure that the backups are functioning correctly and that they can reliably restore the VM to its desired state.

Conclusion

In conclusion, managing data in virtual environments requires a thorough understanding of both VM snapshots and backups, as each serves critical but distinct roles in data protection. Snapshots are best suited for short-term data recovery needs, providing quick and efficient means to revert a virtual machine to a previous state during testing or updates. However, they are not standalone solutions for data security because they depend on the integrity of the original data storage and are stored within the same system.

On the other hand, backups are indispensable for comprehensive, long-term data security. They are robust and independent, making them essential for recovering from significant data loss incidents like system failures, malware attacks, or catastrophic events. Backups ensure that data can be restored from an external source, providing a higher level of resilience against a range of threats.

Effective data management in virtual environments also involves adhering to best practices such as regular scheduling of snapshots and backups, prudent lifecycle management of data copies, and securing stored data through encryption and offsite storage. Furthermore, automating these processes where possible can enhance accuracy and consistency, while regular testing of backup integrity ensures that data recovery processes are reliable and ready when needed.

Ultimately, the combined use of VM snapshots for immediate recovery needs and comprehensive backups for long-term protection forms a robust defense against data loss, supporting both operational continuity and compliance with data governance standards. This strategic approach enables organizations to leverage the benefits of virtualization while minimizing risks associated with data management and protection.

FAQ

  • Can VMware snapshot be used as a backup?

    Avoid using VMware snapshots as backups. A snapshot file merely logs changes to the original virtual disk, creating a placeholder disk (virtual_machine-00000x-delta.vmdk) to store data changes from the time the snapshot was taken.

  • Why is a snapshot not a backup?

    Snapshots Are NOT Backups

    Snapshots operate at the storage block level and do not recognize the Oracle block structure. More importantly, they are fundamentally different from backups, as they consist of pointers rather than actual data blocks.

  • What is a snapshot of a VM?

    A VMware snapshot is a point-in-time copy of a virtual machine (VM) in a VMware environment. While snapshots are useful for restoring a VM to a previous state after a system failure or error, they are not suitable for creating VM backups.

  • Should you snapshot virtual machine memory?

    Administrators create snapshots as a failsafe to revert a VM to a specific point in time. For instance, they often take snapshots as a precaution when conducting tests, performing software updates, uninstallations, or making other changes in the virtual environment.

  • What is the difference between snapshot and clone in virtual machine?

    A snapshot captures the state of a virtual machine at a specific point in time, preserving the entire contents of the VM's disk. In contrast, a clone is a copy of an existing virtual machine that shares the same virtual disk as the original.

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