CheckpointInfo

total size of the data files, as the source reported them. Not the space the checkpoint occupies — see hardLinked, where the answer is close to nothing.

the directory that now holds the checkpoint. Opens as a store.

files written, which is the segments plus their sidecars plus a manifest and a CURRENT.

whether the data files are links to the originals rather than copies. A link costs a directory entry and no data blocks, which is what makes a checkpoint cheap enough to take often; it also means the checkpoint shares its blocks with the source, so it is a consistent view and not an off-site backup.

segments the checkpoint holds.

the sequence the checkpoint was taken at. Every commit at or below it is in the copy; nothing above it is.