Daily Snapshots - Previous Snapshot Grows When Deleting Snapshot Before

[RedHatcc]

Hi. I am new to NetApp, so please excuse the probably simple question. When I log into our SVM and run the following: 

snapshot show volNameHere

I get the list of the snapshots. This is a very inactive volume, so snapshots are very low in size (about 1MB). However when I run the following command to delete the snapshot:

snapshot delete -volume volumeNameHere -snapshot snapshotNameHere

It removes the snapshot, however it makes the snapshot before it grow to almost its same size. 

My question is how are these snapshots linked so when I delete say the one from Friday, the snapshot from Thursday takes its size? Thanks in advance!

[GrumpyOldMen]

When you don't have an active filesystem, you mean not a lot of data is changed in between taking snapshots. Data changes within the different snapshots are carefully monitored by WAFL. When you delete a snapshot, WAFL will go through it's file system and only those blocks not used anymore by the other snapshots will be deleted. So in your case, not a lot of space is freed.

As you are a newbee it's important to understand how the snapshotting is working within WAFL. This is different then other vendors are doing snapshotting!!! Please have a look at following links.

http://reyansh-netapp.blogspot.be/2013/04/normal-0-false-false-false-en-us-x-none_20.html

https://www.eigenmagic.com/2009/10/17/why-netapp-snapshots-are-awesome/

http://doc.callmematthi.eu/static/webArticles/NetApp%20-%20SnapShot.pdf