An IT infrastructure perspective on optimizing business applications
A comparison between Oracle (Active) Data Guard and EMC replication for disaster recovery purposes
This is an article I wrote a while ago for customers’ Database Administrators (DBAs) and application managers, that helps them in selecting the right Disaster Recovery tools for their business applications.
It is slightly modified to update new insights and to make it more readable on the web.
Slightly off-topic here considering my normal focus on business applications (or actually, maybe not, decide for yourself).
On the Dutch ICT news sites it is currently a big topic. And the impact for the whole internet is probably still underestimated. What happened? On August 29 2011, I read a news post on webwereld.nl (a Dutch ICT news site) that Iran (actually it seemed to be Iranians but this is still not sure) could tap internet traffic to GMail. This happened because they used an SSL certificate that was signed by the Dutch Certificate Authority Diginotar. Diginotar is a Dutch company providing PKI (Public Key Infrastructure) “certificates” for secure connections, both for regular commercial customers and for the Dutch government. Ouch!
(more…)
Maybe you have heard the story of the Monkey Experiment. It is about an experiment with a bunch of monkeys in a cage, a ladder, and a banana. At a certain point one of the monkeys sees the banana hanging up high, starts climbing the ladder, and then the researcher sprays all monkeys with cold water. The climbing monkey tumbles down before even getting the banana, looks puzzled, wait until he’s dry again and his ego back on its feet. He tries again, same result, all monkeys are sprayed wet. Some of the others try it a few times until they learn: don’t climb for the banana or you will get wet and cold.
The second part of the experiment becomes more interesting. The researcher removes one of the monkeys and replaces him with a fresh, dry monkey with an unharmed ego. After a while he spots the banana, wonders to himself why the other monkeys are so stupid not to go for the banana, and gives it a try. But when reaching the ladder, the other monkeys kick his ass and make it very clear he is not supposed to do so. After the new monkey is conditioned not to go for the banana, the researcher replaces the “old” monkeys, one by one, with new ones. Every new monkey goes for the banana until he learns not to do so.
Eventually the cage is full of monkeys who know that they are not allowed to climb the ladder to get the banana. None of them knows why – it’s just the way it is and always has been…
(more…)
For many years, EMC customers have been using storage replication technology to create copies of entire databases. Using storage cloning has many advantages over other mechanisms (file copy, tape restore, and the like). Most significant is that EMC storage can create near-instant copies of large applications without significant performance overhead. The reason is that the storage system is using its huge internal bandwidth and a couple of smart tricks to create the copy, therefore bypassing the host I/O layer.
In other words, a server running a database does not have to move a single bit of data for creating a copy of a multi-terabyte database.
Last year, EMC announced a new virtualization product called VPLEX. VPLEX allows logical storage volumes to be accessible from multiple locations. It boldly goes beyond existing storage virtualisation solutions (including those from EMC) in that it is not just a storage virtualisation cluster – but merely a storage federation platform, allowing one virtualized storage volume to be dynamically accessible from multiple locations, as if they were connected through a wormhole, and being built from one or more physical storage volumes.
