Backup and restore considerations when placing tables on disks
When you decide where to place your tables or fragments, remember that if a device that contains a dbspace fails, all tables or table fragments in that dbspace are rendered inaccessible, even though tables and fragments in other dbspaces are accessible. The need to limit data unavailability in the event of a disk failure might influence which tables you group together in a particular dbspace.
Although you must perform a cold restore if a dbspace that contains critical data fails, you need only perform a warm restore if a noncritical dbspace fails. The desire to minimize the impact of cold restores might influence the dbspace that you use to store critical data.