Đang chuẩn bị nút TẢI XUỐNG, xin hãy chờ
Tải xuống
Oracle RMAN 11g Backup and Recovery- P12: Oracle, yet another edition of our RMAN backup and recovery book has hit the shelves! Oracle Database 11g has proven to be quite the release to be sure. RMAN has new functionality and whizbang new features that improve an already awesome product. RMAN has certainly evolved over the years, as anyone who started working with it in Oracle version 8 can attest to. | 518 Part IV RMAN in the Oracle Ecosystem ync and split technology is an example of an innovative and challenging solution for storage recovery that complements or duplicates many of the features RMAN can accomplish independently. Over the past five years sync and split has become a widely used technology to provide immediate and very fast system recovery at the storage hardware level. In this chapter we will provide an overview of what sync and split technology refers to. We won t be discussing any single implementation in particular but rather discussing the implications for RMAN and database backups. After the overview we go into the specific steps required to integrate sync and split solutions into an RMAN backup strategy. Sync and Split Broken Mirror Backups In the beginning doing sync and split backups involved nothing more complicated than extending the functionality of hardware mirroring. The best way to explain this statement is through an example. Suppose we have a disk controller that has two hard drives. For redundancy we set the RAID level to 0 1 so that we are mirroring everything on disk A to disk B. This gives us immediate protection against any kind of hardware failure on either disk A or disk B. The next step then is to try to leverage the hardware mirror to provide logical fault tolerance. That is the goal of sync and split technology to provide a fallback position in case of some failure that has occurred on both copies in the mirror. For example suppose that a user has deleted the entire oracle software tree or the oradata directory. Such a deletion would immediately occur at both copies in our mirror so having a mirrored copy would do us no good. So what is the solution The innovation is that any mirrored disk group may have two mirror groups but may only ever have one mirror currently writing the identical bits as the primary disk group. Let s build an example with three logical volumes A B and C all dedicated to the same data. Volumes A B and