It is filesystem snapshot.
We have seperate snapshots for each filesystem and these are maintained inside the database.
Snapshots are current views of your filesystems. Basically, snapshot lists patches and versions of files in your filesystems.
It just do the following update.
Note that I didn't include the select of that update, but it is clear that It flips the snapshot info in ad_snapshots. I mean it makes type C -> P and P -> C and G -> Q and Q -> G)
So, the same logic of the cutover applies for it as well..
This is not documented in anywhere... I checked and asked, no info yet...
But, what I can say is; C is the same as P and Q is the same as G ..
How can I think like this? Because as you see the following update , it sets C to P and G to Q and vice versa.
Like fs1 and fs2 is the same, I believe "C and P" and "G and Q" are the same things . These are for cutover.. It changes the filesystems and it changes/cutovers the snapshot types accordingly (using these letters)...
This is what I think actually...