Cassandra provides a simple backup tool called
nodetool snapshot to take incremental snapshots and back up of data. The
snapshot command flushes MemTables to the disk and creates a backup by creating a hard link to SSTables (SSTables are immutable).
Hard link is a directory entry associated with file data on a filesystem. It can roughly be assumed as an alias to a file that refers to the location where data is stored. It is unlike a soft link that just aliases filenames, not the actual underlying data.
These hard links stay under the
data directory, which is placed under
The general plan to back up a cluster roughly follows these steps: