Question of auto delete snapshot

[Harry49528]

Hello, I am new to NetApp and currently I am trying to create a snapshot schedule. Reading some docs, it says that the auto delete will be triggered if it reach the snapshot reserve (trigger is in snap_reserve). However, I can always find there is Snapshot Overflow. And therefore, I wonder will the auto delete be triggered if the number of copies not reaching its maximum. For examples, if a volume is set a daily snapshot with 5 maximum copies, will it auto delete if the size of snapshot is more that snapshot reserve on the third day?

[Tas]

Not if there is enough space in the volume/aggregate to contain the data and snapshots.


Anastasios A Papadopoulos (Tas)
IT Storage Architect

[cid:image002.png@01DB1892.84DEB000]
Systems Security Certified Practitioner (SSCP)

[Harry49528]

Thanks for reply, but in my situation, I have received lots of alarms that the volume is out of space so I believe this is not the reason. 

[ChLokesh]

Hello Harry,

No, the autodelete will not be triggered if the size of snapshot is more that snapshot reserve.
In such case a snap spill would occure.
Snapshot spill means that your backups exceed the allocated space of snapshot reserve and spill into the active file system.

Hope this information helps.

[Harry49528]

If my understanding is correct, the only solution is to increase snapshot reserve capacity in order to make the autodelete work. Am I right?

[Ashun · Accepted solution]

hi Harry

In NetApp, snapshot scheduling and management can be a bit nuanced. Here’s how it generally works in relation to your question about snapshot reserves and auto-deletion:

1. **Snapshot Reserve**:

This is the percentage of the volume space that is set aside explicitly for storing snapshots. If the amount of space used by snapshots exceeds this reserve, NetApp will start to automatically delete older snapshots to free up space.

2. **Maximum Copies**:

This is the maximum number of snapshots you want to keep for a volume. For example, if you have a daily snapshot schedule with a maximum of 5 copies, you should expect to retain up to 5 snapshots at any given time.

3. **Auto Delete Trigger**:

The auto delete feature will trigger if the snapshot space usage exceeds the configured snapshot reserve, regardless of whether or not you've reached the maximum number of snapshots.

So in your example, if on the third day the size of the snapshots exceeds the snapshot reserve, the system will initiate the auto-deletion process even if there are fewer than 5 snapshots present. It will prioritize deleting the oldest snapshots first until the snapshot space is back within the limits of the snapshot reserve.

Summary:
- Auto deletion is based on exceeding the snapshot reserve.
- The number of snapshots can be less than the maximum allowed, but if the usage exceeds the snapshot reserve, older snapshots will still be deleted.

In my opinion

Increasing the snapshot reserve capacity can help ensure that your snapshots have enough space to be retained without causing the volume to run out of space. However, this is not the only solution. I usually choose the following methods

1. **Increase Snapshot Reserve**:

Yes, increasing the snapshot reserve can allow more snapshots to be held without triggering alerts. This helps in managing automatic deletions effectively.

2. **Modify Snapshot Schedule**:
Adjust the frequency of snapshots taken. Reducing the number of snapshots created can help manage space better.

3. **Delete Unused Snapshots**:

Manually delete any old or unnecessary snapshots if they are not needed for recovery purposes.

By combining these strategies, you can better manage your volume's space and ensure the snapshot deletion process works effectively.

[Harry49528]

Got it. Thanks for your help.