Snapshot size references the "New" data since the prior snapshot.
You may be asking, “What is new data?”
- “New Data” = anything changed between snapshots; regardless of whether the snapshot “owns” it.
»Data written to the primary volume
»Existing data which is overwritten
»Data no longer used by the primary volume but retained by the snapshot
- “New Data” can almost be called “how much do I need to replicate to the DR site to keep the arrays synchronized”…but that doesn’t fit in the GUI.
»It’s still “New Data” even if all data is actually “owned” by the primary volume and not by snapshots.
- Wait a minute…
»That’s right! The first snapshot on a volume containing 1.7 GB of data will have 1.7 GB of “new data”… the amount of data written since the prior (non-existent) snapshot.
»Also, the amount we need to replicate for the initial replication (replication seeding).
»If you take a second snapshot and delete the first one. The second snap is now….yay! 1.7 GB because it represents all data prior to itself.