- IBM XRC (host-based solution, supported by EMC, HDS, and STK)
- EMC SRDF/A
- HDS HARC.
There are some limitations to the backup and replication solutions. For instance, they can’t correct a data corruption due to a bad transaction or user error and they can grow quite expensive to implement and maintain. The user may have to double their storage footprint and some solutions result in several copies of production data in multiple sites. To create a consistent point-in-time backup usually requires an application outage. Many vendors are delivering techniques to ensure data consistency across storage devices. Several large database customers have successfully implemented some form of hardware replication in the name of DR preparedness.
The replication solutions can allow for a simplified process at the time of a disaster; the user performs some operations at the remote site to render the backup or mirror available to a processor and restarts the database applications. Processing can resume, usually within a few hours of arrival at the remote site. These solutions are attractive to a customer willing to spend the extra money for replicating data. The user can control data loss and reduce recovery time. The hardware solutions are effective tools for restoring to a point-in-time backup or restarting from a mirror in the event of a site-wide disaster.
What can cause a database outage? Some outage events are planned:
- Application database maintenance
- Data migration
- Schema change implementation