Many IT environments operate their systems in more than one data center. In order not to have any data loss in the event of a failure of an entire data center, the data is mirrored between 2 or more data centers. The mirroring can be realized by the storage (storage based mirroring) or by a volume manager (LVM in the case of AIX) on the server (host based mirroring). In the article Mirror Pools: An Introduction we look at mirroring using AIX Logical Volume Manager and Mirror Pools. The aim is to show how the correct mirroring of logical volumes can be implemented with the help of mirror pools. In larger environments with many physical volumes, maintaining correct mirroring without mirror pools is difficult and a challenge for the administrator.