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Snapshots are a practical tool for VMware admins, and it is easy to capture a point-in-time state and roll back quickly when needed. They’re widely used for testing, upgrades, and short-term protection because they provide fast and flexible recovery.
To get the most out of snapshots without affecting performance or storage, it’s important to use them properly and follow VMware snapshot best practices.
What Is a VMware Snapshot and How Does It Work
A VMware snapshot saves a virtual machine’s state at a specific point in time. When you create a snapshot, the original virtual disk (VMDK) becomes read-only, and all new changes are written to a separate delta disk. This lets you restore the VM from the snapshot if an update or configuration change causes problems.
To make this work, VMware reads data from both the base disk and the delta files. Each new snapshot adds another layer to check. The more layers there are, the slower disk performance can become. For this reason, snapshots are designed for short-term use, not long-term storage.
Core VMware Snapshot Best Practices to Follow
Good snapshot habits reduce risk and improve performance. Here are the key best practices for managing VMware snapshots.
1. Keep Snapshots Short-Lived (24–72 Hours Max)
VMware’s official guidance emphasizes keeping snapshots temporary, with a recommended maximum lifespan of 72 hours. Snapshots are designed for short-term rollback scenarios after all.
If you leave snapshots on for days or weeks, the extra data files they create will keep growing. This makes it take longer and be riskier when you finally try to clean them up.
For most setups, it’s best to delete snapshots within 24 hours. This is the basic safe way to manage VMware snapshots.
Note: Snapshots older than 72 hours are not officially supported for production stability and are a common cause of slow consolidation and datastore issues.
2. Limit the Numberof Snapshots Per Vm (≤ 2–3 Recommended)
VMware can technically support up to 32 snapshots in a row. But too many snapshots make storage hard to manage and slow down your VM. Most IT teams suggest keeping no more than 2–3 snapshots per VM.
Each new snapshot adds an extra layer for the storage system to read. This extra work directly slows down your VM during normal use. Keeping snapshot chains short is one of the easiest ways to keep performance steady.
3. Don’t Use Snapshots as Backups
This is one of the most important VMware snapshot best practices, as many people wrongly think that snapshots equal to backups. But snapshots rely completely on the original main disk. If the main disk is lost or damaged, snapshots cannot be restored.
VMware’s guidelines clearly separate snapshots from backups. Snapshots let you roll back recent changes. Real backups keep data safe long-term, with copies stored separately for extra protection.
Tip: Always pair snapshots with a dedicated backup solution. Snapshots are for rollbacks, backups are for disaster recovery.
4. Avoid Snapshots on High-I/O Workloads
Systems like SQL Server, Exchange, and large databases handle a lot of data very quickly. When you use snapshots on these VMs, the extra files created by the snapshots grow fast. They can quickly use up all available storage space and make the system run poorly.
For these high‑activity systems, it’s best not to take snapshots during busy hours. Fast‑growing snapshot files can cause the VM to slow down or freeze. They can also lead to delays when cleaning up snapshots, and if space runs out, the system may even stop working entirely.
5. Monitor Datastore Free Space Before Creating Snapshots
Users should check the free space in the datastore before they create any snapshot. VMware suggests keeping at least 20% free space so snapshot files can grow without problems.
Snapshot files can become as large as the original VM disk. If users create a snapshot on a nearly full datastore, the space may run out completely. When space runs out, many VMs on the same storage may stop working.
Note: If your datastore is already above 80% utilization, avoid creating new snapshots until additional space is available.
6. Always Consolidate after Deleting
When users delete a snapshot, the system does not always clean up leftover files automatically. Sometimes these unused files stay behind and keep taking up space. They also make the system run slower than usual.
So, the best practice here is that administrators should check the vSphere Client for a “Needs Consolidation” warning. Making sure all leftover files are fully cleaned up helps save storage space and keeps the disk system working properly.
7. Schedule Snapshots outside Peak Hours
Creating or deleting a snapshot can cause a short, sudden increase in data activity. The system may also pause briefly while it locks the disk. These effects can make the system feel slow for users if they happen during busy hours.
For better performance, you should plan snapshot tasks during maintenance times or when the system is not busy. This helps avoid performance issues and keeps regular work running smoothly.
8. Use Quiescing for Application Consistency
For applications like databases or email servers, a normal snapshot may not capture all data at the same moment. Some files may still be changing while the snapshot is taken.
Quiescing briefly pauses application activity and puts the file system into a stable state before the snapshot. This makes restores more reliable, especially for important business systems that handle frequent data changes.
Tip: For SQL and Exchange VMs, always use VMware Tools quiescence to avoid corrupted application states after restore.
9. Automate Cleanup Policies
Tracking snapshots manually often leads to mistakes, and old snapshots are a common cause of storage problems. Over time, it’s easy to forget which ones are still needed.
Automation tools, such as PowerCLI, can monitor snapshots, find outdated ones, and send alerts. This best practice keeps snapshots from staying too long and helps avoid performance slowdowns or unexpected disk space issues.
10. Test Restore Regularly
A snapshot matters if it can actually restore the VM when needed. Administrators can test snapshot recovery and cleanup steps regularly in non-production environments to make sure everything runs as expected.
The difference between “Revert to Snapshot” and “Delete All” helps ensure a quick and reliable recovery during outages. Regular tests can also make VMware snapshots more predictable and safe.
Step-by-Step: How to Safely Create VMware Snapshots
It is simple to create a snapshot, but safe creation needs a few careful steps. These steps help avoid brief system pauses or storage space issues. With these best snapshot practices for VMware ESXi hosts, you can ensure your recovery points are reliable without impacting production performance.
- Check Datastore Capacity: Before starting, verify that the underlying storage has at least 20% free space. Remember that a snapshot disk can grow to the size of the original disk if left too long.
- Navigate to the VM: In the vSphere Client, right-click the virtual machine, select Snapshots, and then Take Snapshot.
- Name and Describe: Always provide a clear name and a brief description (e.g., “Pre-Patching-Feb-2026“). This helps other admins understand why the snapshot exists and when it can be safely removed.
- Configure Memory and Quiescing:
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- Snapshot VM memory: Only check this if you need to capture the exact running state of applications. Note that this takes longer and consumes more disk space.
- Quiesce guest file system: Check this to ensure the OS and applications are in a consistent state before the snapshot is taken.
- Monitor Task Progress: Watch the “Recent Tasks” pane. Once complete, verify that the snapshot appears in the Snapshot Manager.
Good snapshot management in vSphere also includes setting a calendar reminder right after a snapshot is created. This reminder helps people delete or clean up the snapshot within 24 to 72 hours.
Pros and Cons of VMware Snapshot
Snapshots are very useful for daily work, but they also bring risks.
Pros:
- Instant Recovery: Teams can quickly roll back to a previous state if updates or setting changes cause problems.
- Administrative Safety: Snapshots act like a safety net. They let admins make changes with the confidence that mistakes can be easily undone.
- Backup Enablement: Many backup tools use snapshots to save VM data. This process happens without stopping regular work.
Cons:
- Performance Degradation: More snapshots in a chain make the VM run slower. Read and write actions take longer to finish.
- Storage Exhaustion: Snapshot files grow over time. Without right management, they can use all available space. This may lead to full system outages.
- The “Stun” Effect: Creating or deleting snapshots can briefly pause VM activity. This pause may disconnect important apps or databases.
Snapshots Aren’t Enough – Back Up Your VMware with i2Backup
While following best snapshot practices for VMware ESXi hosts is vital for short-term recovery, it is not a complete data protection strategy. A snapshot depends on the base disk; if the datastore fails, the snapshot is lost.
i2Backup provides a comprehensive, full-stack workload data protection solution that ensures your environment remains resilient.
Key Features of i2Backup include:
- Agentless VM Backup: Provides agentless protection at scale for VMware, Hyper-V, and other mainstream platforms without installing agents. It uses native virtualization APIs for seamless backup, replication, and migration with zero impact on production.
- Multi-dimensional Protection: Employs write-once-read-many (WORM) compliant storage to make backups immutable, preventing unauthorized deletion. It also supports AES and SM4 standard encryption during transmission with strict access controls.
- Light-fast Recovery: Includes Instant VM Recovery to remotely mount backups for low Recovery Time Objectives (RTOs). It also supports file-level recovery, allowing you to restore specific folders or database entries without a full system restore.
- Intelligent, Centralized Management: Features a user-friendly B/S web interface for centralized control of all workloads. Its “set-and-forget” workflow automates everything from deduplication to Smart Cleanup policies that remove obsolete backups to optimize storage.
- Scalable for the Future: A distributed architecture that delivers seamless horizontal scaling to accommodate data growth. It supports a wide range of storage media, including local disks, tape libraries, NAS, and more.
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VMware Snapshot FAQs
Q1: How many snapshots can I have on a single VM?
Stick to 2–3 snapshots per VM. Longer chains add storage layers and increase VM latency, hurting overall performance.
Q2: Do snapshots impact VM performance?
Yes. Snapshots create extra read/write overhead. Use them only for short tasks and delete quickly to restore full speed.
Q3: Can snapshots protect me if storage fails?
No. Snapshots depend on the original base disk. If storage fails, both the VM and its snapshots are lost.
Q4: Why the 72-hour limit for snapshots?
Snapshots are temporary. Older snapshots bloat delta files, slow consolidation, and risk storage issues—72 hours keeps operations safe and efficient.
Q5: What if I leave snapshots unmanaged?
They grow, waste space, and slow VMs. Severe cases can fill datastores and crash all VMs on the volume.
Q6: Should I snapshot SQL/Exchange VMs?
Avoid it during peak hours. High I/O makes delta files grow fast, risking space issues and VM stuns. Use quiescing if snapshots are necessary.
Q7: How to check if consolidation is needed?
Look for the “Needs Consolidation” warning in the vSphere Client. Run consolidation to clean up leftover delta files.
Q8: Revert vs. Delete snapshot—what’s the difference?
Revert rolls back to the snapshot state and discards changes. Delete merges changes into the base disk and keeps all updates.
Q9: Do snapshots work as backups?
No. Backups are independent copies; snapshots rely on the base disk. Always use a dedicated backup tool for data protection.
Q10: How much free space do I need for snapshots?
Keep at least 20% free space on the datastore. Delta files can grow to match the base disk size, so space prevents outages.
Conclusion
VMware snapshot best practices include keeping snapshots for less than 72 hours. They also include limiting the number of linked snapshots and checking available storage space often. These habits help teams use snapshots safely and keep vSphere and ESXi systems stable and fast.
IT teams should know that snapshots only provide short-term protection. For full, long-term data safety and disaster recovery, a dedicated backup solution such as i2Backup will keep enterprise systems secure and ensure data resilience.
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