K‑safety sets fault tolerance for the database cluster, where K can be set to 0, 1, or 2. The value of K specifies how many copies Vertica creates of segmented projection data. If K‑safety for a database is set to 1 or 2, Vertica creates K+1 instances, or buddies, of each projection segment. Vertica distributes these buddies across the database cluster, such that projection data is protected in the event of node failure. If any node fails, the database can continue to process queries so long as buddies of data on the failed node remain available elsewhere on the cluster.
For more information, see Designing for K-Safety.