Overview Of Oracle H.a.r.d. And Database Validator Operations - HP StorageWorks P9000 User Manual

Figure 3 Typical database system configuration

Overview of Oracle H.A.R.D. and Database Validator operations

The following figure shows a typical system configuration with Database Validator. The Oracle
Hardware Assisted Resilient Data (H.A.R.D.) feature protects against data corruption. The Oracle
application software computes checksums that are included with every data block written to disk.
The Database Validator feature recomputes the checksums upon receiving data blocks to be written
to Oracle database volumes. In the event that the storage system receives a corrupt block, the I/O
operation is rejected with a checksum failure error. The ability of the storage system to recognize
that it has received corrupt data and reject the I/O prevents corrupt data from being written to the
database, thus eliminating "silent" data corruption. Without Database Validator (but with Oracle
H.A.R.D.), corrupt data is discovered, but only when the data is read back at a later date.
Figure 4 Typical database system configuration with Database Validator
Storage systems already perform extensive checksum-type validation of data integrity from the
point of entry through the entire storage system. The new Database Validator feature detects
corruption occurring outside the storage system by checking write data upon receipt. The objective
is to prevent corrupt data destined for Oracle volumes from being accepted by the storage system.
Overview of Oracle H.A.R.D. and Database Validator operations 7