We are implementing Dual Load in a mainframe environment. This implementation is divided into several phases, and replicates existing schedule i.e. running two Jobs which will be loading same data into two different databases: System A, and System B. In case of disaster with System A, System B will be accessible for Read, and Load.
This however add plenty of overhead for maintenance, storage(both mainframe, and ETL server) etc, and on-going development cost to any new project (since the project would do this for whole EDW). If we currently have 1000 load Jobs in total, after this implementation, we would have additional 1000 load Jobs.
One expert suggested, instead of replicating the whole process, this could have been done with Shadow technology, where EDW is replicated to redundant System B(frequency can be determined i.e. every night after business hours etc). This would avoid schedule replication to the System, will be transparent to the user, saves developmental, maintenance, and hardware cost. Someone said, if we implement with Shadow technology, if System A is hit, System B cannot be used for loading (only read), and hence useless. The objective is not merely read accessbility, but also write (Load) continuity as well.
Another expert said Teradata does Not support Shadow technolgy (is that true? please answer.)
Now, after reading a long detailed background, do you think there is a way to have System B available for Read, and Write without replicating the whole schedule, adding two Jobs which does the same data load, and adding resources cost etc ? Remember your solution should be transparent to the development process, and users.
By "shadow technology", I assume you mean a read-only mirror that is maintained directly out of the disk array system. Teradata does not currently support that kind of solution.
Supported alternatives to dual loading include the replication solution that we offer jointly with GoldenGate software, but this solution has significant throughput and scalability limitations. You may want to take a look at the Replication Solutions Overview document in our customer publications library.
By "Shadow Technology" I meant standby system (SYSTEM B), which relies on System A (default) for its data, but when System A goes down for maintenance or disaster, System B takes over, and switch over is almost transparent to the user. This saves plenty of cost that our company will be incurring by not choosing alternatives to Dual Load and running parallel Loading/Reading process.
1) Does your company offer any solution that is transparent to the user? 2) I tried to search 'Teradata Replication Services' on Teradata.com but this link doesn't work: http://www.teradata.com/t/page/130607/ any other place on web can I find this alternative solution?
As I understand it, there is a Teradata product called Query Director product that could make the failover transparent to some users, but I don't think it can transparently redirect load jobs.
The Replication Solutions Overview (publication number B035-1152-067A) is included in the Teradata User Documentation CD at least since release 6.1. If you are a Teradata customer you should have that already. The URL to download it seems to be "http://www.info.teradata.com/eDownload.cfm?itemid=072600033".