1) When we upgraded from 7 mode to C-Dot, the size of our daily snapshots for our biggest volumes increased by a factor of 10, a huge increase (hence an oversized snapshots issue). We've yet to understand why.
2) On other volumes, we are seeing deletions that don't tally with snapshot sizes. eg 100GB+ of data deleted, but resulting in a 100MB snapshot (so an undersized snapshot issue).
I won't go into too much detail at this point, as we are still undergoing testing, especially with the second issue that has only recently come to light.
This is why we are looking for some deepdive documentation to cement our understanding of snapshots at a technical level, so we can better engage support.
We did a copy free transisition using the 7MTT tool.
Yes this is NAS filesystem data, no VMs no databases.
Whilst snapshots may be simple "in theory", there is a lot more to snapshots than just recording changed blocks. For example how space utilization is calculated, when it is calculated, what is classed as a changed block, and system content that exists in a snapshot that you can't even see e.g. /.copy_offload/.tokens etc.
That's why we're looking for documentation to gain a better understanding of how this works at a lower level, if it exists