Well, he went and did it again, Chris Shaw started yet another web chainpost. This time he tagged Brent Ozar and Brent tagged me and put the pressure on me to be “witty” in my response. I swear, it’s like he doesn’t even know me.
So, this quiz is a two parter, which makes me think of those philosophy exams I had during my freshman year in college. The professor would make us think it was easy by saying “hey, it will be multiple choice” and you would think that meant maybe four options at the most but then you would sit down and there would be eight options with answers like “a and b but never c” or “a or b and sometimes c” and you just wanted to ask the professor why he hates other humans so much.
So, here are my answers. You’re welcome.
Do you feel that you have a reliable SAN solution? If so, what’s the secret?
Yes. The secret is Calgon, everyone knows that. And if you run out of Calgon just buy a boatload of cache.
Explain Database Mirroring in layman’s terms
Doesn’t that depend on the layman I am speaking with? Or should my explanation work for all layman? Wait a minute, what is a layman anyway? Because I thought that was the same as a Freemason or a Stonecutter. Be right back.
OK, a layman is someone identified as a non-expert in a given field. So, you want me to explain database mirroring in a way so that anyone, including a child, could understand it? How about this:
Long ago, in ancient times, in the time before time, people were asked to make copies of their work. This led to some very interesting inventions throughout history, most notable the printing press, the polygraph, and ultimately the modern day copy machines. But(t) as society progressed to the point where deliverables were measured in fractions of a second as opposed to days or weeks, these archaic methods were no longer good enough. There was more and more demand placed upon people to deliver the same piece of information into many different places all at the same time without any loss of service.
Soon a great battle took place between two giant beasts named Cluster and Log Shipping, who had easily beaten down the inferior SQL Replication in a pay-per-view event two months prior. Cluster and Log Shipping battled for years, neither giving an inch to the other, until such time that they were both badly beaten, weakened, and barely able to stand.
At that time a great hero rose from the ashes of Clusters and the ruins of Log Shipping. The hero’s name was Database Mirroring and promised that everything was going to be different. Database Mirroring promised real time synchronization of your data without the hassle of log shipping. Database Mirroring promised faster fail over without the need for a cluster. In short, Database Mirroring promised the best of all other technologies, with none of the shortcomings, and even brought along a witness to attest to its abilities.
The end. Sweet dreams.
OK, so I am a layman who’s trying to learn.
Why is it so much better? It’s more expensive: you need another server. Not many business have that, so I really need a compulsive argument other than ‘the contractor who has 20-odd years experience on me says this is a Good Thing’.
Ta muchly
J
Jane,
Wouldn’t clustering, log shipping, and replication also require another server? I can certainly understand that not every business would have servers just laying around, but if you are looking at HA options perhaps you could help me understand which ones do not require extra hardware?
And I did not say explicitly that mirroring was better; only that it claims to be better by offering the best of other technologies without the headaches of each. Mirroring does not require shared disks and resources like a cluster. It does not require you to ship your logs across the WAN. It does not mean you need to spend time fixing replication when it breaks.
Mirroring commits transactions on one server and then on the second server. You can either wait for the second server to respond (synchronous) or not (asynchronous) to the primary server. This reduces the load on your network, you don’t need to spend time doing backups and restores, there is no replication to break that you need to fix, and you don’t need to build a quorum of disks. What’s not to love, right?
Tell me more about why you would be considering mirroring and I can try to help you understand if it is the right tool for you to use.