Ensuring your systems run smooth even when your data center has a hiccup, or a real disaster strikes is critical for many companies to survive when hardships befall them. As we enter the age of the zettabyte, seamless disaster recovery has become even more critical and difficult. There is more data than we have ever handled before, and most of it is very, very big.
Most disaster recovery (DR) sites are in standby mode—assets sitting idle, waiting for their turn. The sites are either holding data copied through a storage area network (SAN) or using other data replication mechanisms to propagate information from a live site to a standby site. When disaster strikes clients are redirected to the standby site where they’re greeted with a polite “please wait” while the site spins up.
At best, the DR site is a hot standby that is ready to go on short notice. DNS redirects clients to the DR site and they’re good to go.
What about all the machines at the DR site? With active/passive replication you can probably do queries on the slave site, but what if you want to make full use of all of that expensive gear and go active/active? The challenge is in the data replication technology. Most current data replication architectures are one-way If it’s not one-way, it can come with restrictions—for example, you need to avoid opening files with exclusive access. Continue reading