What is snapshot used for?

Snapshots in computing refer to the state of a system at a particular point in time. Snapshots allow you to capture the status of files, databases, virtual machines, or even entire filesystems for backup, replication, analysis, or recovery purposes.

What is snapshot used for?

Benefits of using snapshots

Using snapshots provides several key benefits:

  • Point-in-time recovery – If files or systems get corrupted, snapshots allow you to roll back to an earlier known good state. This makes recovery much quicker and easier.
  • Version history – Snapshots create incremental file versions over time that you can browse through to compare changes. This helps track edits and meet compliance requirements.
  • Replication – Snapshots facilitate copying or synchronizing data across systems via incremental updates. This is faster than full copies.
  • Backups – Taking periodic snapshots lets you back up systems without downtime or impacting performance as much as full backups. Snapshots use less storage too.
  • Testing and analysis – Snapshots allow testing the effect of changes, experiments, or upgrades by sandboxing them separate from production systems. You avoid impacting real users this way.

Types of snapshots

There are a few different types of snapshot technologies:

  • Volume shadow copies – This feature of Windows Server and client OSes allows taking snapshots of disk volumes to create restore points and previous versions of files.
  • Storage array based snapshots – Advanced RAID storage devices often have snapshot abilities built-in to support applications like virtualization, databases, and file servers.
  • Cloud snapshots – Cloud platforms like AWS, Azure, and GCP provide snapshot functionality to backup virtual machine disk volumes for quick restores.
  • Hypervisor snapshots – Hypervisors like VMware ESXi and Microsoft Hyper-V permit snapshotting live virtual machines to rapidly save and restore their state.
  • Application snapshots – Some applications like Microsoft SQL Server integrate with volume shadow copies to generate transactionally consistent snapshots of databases.

Snapshot use cases

There are many scenarios where admins and developers will use snapshots:

Data protection

  • Schedule periodic snapshots as part of a backup scheme for rapid recovery of deleted or corrupted files. Often snapshots integrate with backup tools.

Version control and archives

  • Leverage snapshots to retrieve previous versions of documents for collaboration, legal compliance, or analysis.

Testing software changes

  • Use snapshots to safely test OS updates, application upgrades, or infrastructure changes without impacting production systems.

DevOps integration testing

  • Automate snapshotting and restoring test servers to validate app deployment pipelines before promoting to staging or production.

Database copies

  • Generate read-only database copies from production via snapshots to use for analytics, reporting, or development without performance impact.

Virtual machine management

  • Quickly save the state of a VM and return to it later for multi-phase tasks, contingencies, or asynchronous processes.

Disaster recovery systems

  • Replicate snapshots to remote servers and sites per your business continuity plan as part of resilient IT infrastructure.

Best practices for working with snapshots

Follow these guidelines to get the most out of leveraging snapshots:

  • Schedule recurring, consistent snapshots for reliable recovery points.
  • Define appropriate retention periods per regulatory and business continuity needs.
  • Test restoring from snapshots periodically to verify integrity.
  • Document processes, storage locations, and naming conventions.
  • Secure snapshot files with role-based access controls where authorized.
  • Analyze storage requirements and monitor growth over time.
  • Automate snapshots linking them into backup systems, testing workflows, etc.
  • Integrate with monitoring to track status and receive alert notifications.

Key considerations around snapshots

While snapshots provide immense value for data protection, management, and recovery, be aware of a few constraints:

  • Additional storage is required to store snapshot data based on the rate of change.
  • Too many snapshots can over consume resources and storage capacity. Establish retention policies.
  • Synchronizing many snapshots across distributed systems introduces latency and bandwidth considerations.
  • Restores can be slow depending on workload, resources, and volume sizes. Test expected recovery times.
  • Some data may be skipped during crash consistent snapshots without app integration. Understand implications.
  • Encryption should be considered for highly sensitive data captured in snapshots.

Snapshot management tools

There are robust enterprise tools available to help manage snapshot lifecycles:

Veeam Backup & Replication – Powerful, scalable software for protecting VM, cloud, physical system, and app workloads via integrated, policy-driven snapshot management.

CommVault – Data protection and information management solution with sophisticated scheduling, testing, and automation for snapshot-based backup strategies.

Veritas NetBackup – Industry leading backup that integrates with native snapshot tools on primary storage platforms for application-consistent data protection.

Cohesity – Converged secondary data and app solution consolidating backup, snapshots, replication, dev/test, and analytics on a web-scale platform.

Dell EMC RecoverPoint – Continuous data protection utilities leveraging replication of storage array-based snapshots, journaling, vaulting for RPO/RTO.

Actifio – Enterprise copy data management platform reducing proliferation of production data copies via deduplication and virtualized snapshots.

Snapshot integration examples

Snapshots interoperate well with many other enterprise systems and third party tools:

Cloud – Cloud platforms utilize snapshots for backup/recovery, templates, replication across regions/zones. Cloud storage gateways integrate on-prem.

Containers – Orchestrators like Kubernetes have snapshot capabilities to clone stateful app volumes, backing up volumes before patching nodes.

Databases – Apps like SQL Server integrate with Volume Shadow Copy Service for crash-consistent snapshots of data and log files.

Virtualization – Hypervisors provide native snapshot management. Backup tools leverage hypervisor APIs to orchestrate snapshots.

Storage – Advanced SAN/NAS arrays have built-in support for efficient snapshots – replicated for DR and vaulted for retention.

CI/CD Pipelines – Automation tools can snapshot test servers and restore them to validate app deployment processes repeatedly.

Snapshot best practices by OS

Snapshots have distinct utilities and unique syntax across operating systems:

Linux LVM snapshots

The Logical Volume Manager utilizes lvcreate and lvconvert for fast efficient snapshots retaining old blocks as needed when new data gets written.

Windows previous versions and shadow copies

The Volume Shadow Copy Service protects local and shared folders, making them accessible in File Explorer under the properties’ previous versions tab.

MacOS time machine local snapshots

Time Machine enables incremental backup snapshots storing file changes on the startup drive or network volumes allowing point-in-time restores via the Time Machine app.

AWS EBS snapshots

Elastic Block Stores rely on asynchronous compressed snapshots for backup/recovery, which you manage via lifecycle policies or lambda automation scripts.

VMware snapshot manager

This powerful utility facilitates snapshotting VMs via vSphere APIs or PowerCLI automation. Integrates with vRealize Suite.

NetApp ONTAP Snapshot copies

ONTAP enables manual or scheduled Snapshot copies leveraging NetApp hardware efficiencies. Integrates with SnapMirror, SnapVault, and SnapCenter.

Snapshot management automation

Orchestrating and automating snapshot workflows is key to reducing the management overhead for enterprise IT teams overseeing large production environments:

  • Schedule recurring snapshots across servers and devices via cron jobs or batch scripts.
  • Build snapshot, backup, and replication processes around Powershell, Python SDKs, Ansible modules, Terraform providers, or other IaC tools.
  • Follow strict naming conventions for snapshots aided by variables denoting critical metadata like timestamps.
  • Tag snapshot assets in cloud platforms or use custom labels for on-prem resources to track relationships.
  • Design approval gates and rollback procedures supporting change control board standards into the promotion of snapshots across dev, QA, staging environments.
  • Leverage the robust APIs and CLIs of backup technologies to embed snapshot functionality into larger toolchain pipelines.
  • Analyze snapshot logs, telemetry, resource utilization trends, and status alerts as inputs for machine learning ops.

Snapshot management templates

Standardized snapshot policies optimize storage efficiency, data protection, and restore performance by enforcing consistent schedules and retention rules. Here is one template to adapt:

  • Frequency: Hourly, Daily, Weekly, Monthly
  • Retention settings: Hourly (7 days), Daily (30 days), Weekly (90 days), Monthly (1 year)
  • Weekday and time for scheduled automated daily snapshots.
  • Number of snapshots to retain for each scheduled job based on SLA agreements.
  • Amount of storage to provision in the snapshot reserve capacity.
  • Target disks or LUNs to snapshot based on application and importance.
  • Script or playbook to execute pre and post snapshot to flush buffers, freeze I/O, gracefully halt app processes, and unmount volumes prior to create.
  • Replication and sync processes to copy snapshots to secondary on-prem locations or cloud object storage like S3.
  • Data consistency methodologies based on crash-consistent vs app or crash integrated for databases, file-folders, VMs, Kubernetes volumes etc.

Conclusion

Snapshots provide invaluable capabilities to improve data protection, storage efficiency, change tracking, testing practices, disaster resilience and more within enterprise IT environments. Following the guidelines around retention policies, capacity planning, access controls, monitoring, and automation assists admins in effectively leveraging snapshots for operational recovery and enhanced system availability over the long term.

FAQS

  1. What are crash consistent snapshots?
    Crash consistent snapshots capture the state of a system or files at an exact point in time without coordination with applications. This makes restoration quicker, but transaction logs should validate consistency.

  2. How long should you keep snapshots?
    Balance business continuity needs with storage costs. Frequently accessed files may warrant retaining snapshots for months while reversable test instances only need hours or days before deleting snapshot to reclaim space.

  3. Can snapshots replace backups?
    While snapshots facilitate point-in-time restores, they should not replace traditional backups for long-term archiving according to regulatory compliance nor comprehensive disaster recovery protections. Use both.

  4. What is the difference between snapshots and clones?
    A snapshot captures a system state to revert back to that point, while a clone makes a complete standalone copy you run independently in parallel without impacting the original app or VM.

  5. What risks are introduced with snapshots?
    Frequent snapshots can consume substantial storage capacity that continues growing. Too many snapshots also slows down performance during change tracking and increases backup windows.

  6. How does one automate snapshot management?
    Scripting languages, backup utilities, cloud stacks, virtualization platforms and storage suites provide robust APIs to orchestrate snapshots. Use cron scheduling, lifecycle policies, or triggers based on tags and events.

  7. What should you validate after restoring a snapshot?
    Always test thoroughly that restored files or systems match the state needed at that point in time, contain no corruption, mount successfully, and function with other interdependent app components before allowing production access.

  8. Do you need special VM configuration for snapshots?
    Virtual machines, especially mission critical databases, may warrant reserving free disk space for snapshots, aligning disks to 64k blocks, expanding drives in advance, and quiescing file activity via pre and post snapshot scripts.

  9. Can you automate snapshot labeling?
    Yes, when creating snapshots in scripts, CLI calls or backup tools, embed useful metadata like hostname, timestamps, app name and other custom tags into the snapshot label itself for easier identification later.

  10. Should machine learning inform snapshot rules?
    Analyze historical snapshot storage consumption patterns, data change rates, and restore operational analytics to intelligently recommend retention policies on a per- workload basis tailored to SLAs.

  11. Do snapshots work across SAN and NAS systems?
    Enterprise storage arrays and virtualization software converge technologies to enable consistent snapshots across IP/NFS network shares, Fibre Channel SAN volumes and iSCSI LUNs provisioned to hosts.

  12. Can you replicate VM snapshots?
    Absolutely, virtualization platforms provide mechanisms to copy or sync snapshots across datastores, hosts and sites. This facilitates testing scenarios, migrations, and disaster recovery architectures.

  13. How do snapshots play into CI/CD pipelines?
    Tools like Jenkins, Bamboo and GitLab CI automate frequent snapshots of DEV, QA and demo servers in order to roll back testing instances to known baselines before testing the next app build or deployment playbook.

  14. What risks do snapshots introduce for security compliance?
    Snapshots spread copies of sensitive data across more systems. Classify snapshots clearly and restrict access controls properly per testing needs, data types replicated, and backup media rotations aligned to company security program standards.

  15. Do snapshots capture user permissions and metadata?
    File system and application snapshots retain permissions, ownership, timestamps, attributes, and metadata present at the point-in-time snapshot, assuming the backup or replication utility preserves them. Validate this.

  16. How does vSphere protect virtual machine snapshots?
    The snapshots manager tool within vCenter allows admins to configure nodes storing VM snapshots to avoid single points of failure. Snapshots rely on resilient datastores supporting the VMs.

  17. What are space efficient virtual machine snapshots?
    Hypervisor snapshot formats that leverage change block tracking, redirection on write, and native storage integrations greatly minimize capacity consumption by preserving original disk blocks untouched until new incoming writes divert to snapshot files.

  18. How does Microsoft VSS work with SQL Server?
    The Volume Shadow Copy Service facilitates application consistent snapshots of SQL Server using VDI and VSS frameworks to flush buffers, hold writes, complete transactions, release locks, discontinuing logging temporarily while snapshot writes occur.

  19. Do you need agents to snapshot cloud servers?
    Cloud platforms provide native snapshot capabilities for virtual machine disks and object storage buckets without requiring supplemental agents for capture. Automation handles scheduling centralized.

  20. How does CDP differ from snapshots?
    Continuous data protection (CDP) journals changes in real-time to offer finer-grained recovery point objectives measured in seconds vs crash consistent larger intervals between snapshots that may lose recent transactions.

Leave a Comment