An immutable snapshot adds a retention commitment to an existing recovery point. It is useful to understand that commitment before enabling it on business storage. Synology's documentation describes protection against modifying or deleting the snapshot during its protection period, with restrictions that also affect deleting the storage containing it.

Check that the specific NAS model and installed DSM support the feature. Synology documents immutable snapshots on supported models running DSM 7.2 or later; the presence of ordinary snapshots is not enough to establish support. Identify the shared folder or LUN involved before reviewing any setting.

Decide the period before applying it

In Snapshot Replication, an existing snapshot's list and Edit action expose its immutable setting and protection period where supported. Synology states that the immutable setting remains locked until the protection period ends. Treat the final selection as a commitment, not a trial setting that can be shortened immediately afterwards.

For a project share, write down the recovery requirement, expected rate of change and planned storage maintenance. A forthcoming volume replacement or share retirement matters because protected snapshots can prevent deletion of their containing storage. Resolve that timing before enabling a long period.

Plan for space without assuming emergency deletion

Consider how the workload may change during the chosen period. A media project that replaces large working files has different space demands from a mostly static document archive. Review actual capacity and growth with the storage administrator, and keep an agreed response for low-space alerts that does not depend on deleting a protected snapshot early.

Inspect the remaining protection shown for existing immutable snapshots when preparing maintenance. Record the displayed state and date rather than inferring expiry from a folder name. If removal is unavailable, preserve the message and check the protection details before attempting broader storage changes.

Finally, retain an independent recovery arrangement and verify that a required file can be recovered through the supported workflow. Immutability protects a defined snapshot against specified changes; it does not turn every file on the NAS into an offsite backup. Document the protected dataset, selected period and recovery evidence together so the operational commitment remains clear.

Sources: Synology documentation 1.