Hot-hot replication with EMC's SRDF?

Hot-hot replication with EMC's SRDF?

Is hot-hot replication possible with EMC's SRDF? Is it a fair statement that the only way to be hot-hot is to have non-SRDF storage on both the production and disaster recovery sites?

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It's not really a shortcoming of SRDF that prevents it from doing hot-hot replication. Hot-hot replication is also called bi-directional replication, which means that you can update the data on one side of a replicated link, and the changes will be replicated on the other side.

It is nearly impossible to support bi-directional replication over any distance. If you have a copy of a file on both sides of the replication, and both are written to at the same time, which side's writes should be saved, and which side's should be overwritten?

Bi-directional replication can be performed in some replicated databases, where individual transactions can be controlled, but I would be very careful about implementing that feature. If I needed it, I would test it very carefully before using it in production.

Some organizations are content to have a dataset at site A that is replicated to site B, and then a second, independent dataset at site B that is replicated to site A. That arrangement is fine, since each dataset will only be written to by one side at a time.

This was first published in June 2005