問題文
A DBA creates a disk group for database files and has to choose the redundancy. Which statement describes the three levels and the failure groups they require?
選択肢
- All three of the levels mirror the data two ways, and they differ solely in how many failure groups the disk group of the site is allowed to contain at one time.
- Normal redundancy mirrors data two ways and needs at least two failure groups, high redundancy mirrors data three ways and needs at least three failure groups, and external redundancy leaves the mirroring to the storage array and uses no failure groups.
- Normal redundancy and high redundancy both mirror the data two ways, and external redundancy mirrors the data three ways because the array of the site adds a copy of its own to them as well.
- Normal redundancy mirrors data three ways and needs at least three failure groups, high redundancy mirrors data two ways and needs at least two failure groups, and external redundancy leaves the mirroring to the storage array.