Comments on: Get a feel for enterprise block level replication using drbd http://martincarstenbach.wordpress.com/2012/07/02/get-a-feel-for-enterprise-block-level-replication-using-drbd/ Trying to explain complex things in simple terms Sun, 19 May 2013 17:16:26 +0000 hourly 1 http://wordpress.com/ By: goran http://martincarstenbach.wordpress.com/2012/07/02/get-a-feel-for-enterprise-block-level-replication-using-drbd/#comment-2413 Fri, 13 Jul 2012 12:10:57 +0000 http://martincarstenbach.wordpress.com/?p=1405#comment-2413 Hi Martin,

I absolutely agree with your statement “it is ultimately the DBA’s responsibility to get the system back” … and everybody expect that from us!

As of this, I am pretty resistant on using storage replication … my prefered option is DataGuard.

I had a horror story couple a years ago when our team was persuaded by storage guys to use it for replicating database from Frankfurt to Munich (Germany) … and never again.

Unless I have a very very deep insight into details of underlaying storage technology and thoroughly tested, I choose safe way: DataGuard … in case I can decide which solution … if not, then good luck ;-)

Further, from organization point it’s better to have competence and responsibility in only one team for switch/failover rather then having it spread across different organizational units.

regards,
goran

]]> By: Martin Bach http://martincarstenbach.wordpress.com/2012/07/02/get-a-feel-for-enterprise-block-level-replication-using-drbd/#comment-2350 Thu, 05 Jul 2012 21:14:45 +0000 http://martincarstenbach.wordpress.com/?p=1405#comment-2350 Thank you!

And you were right, I have updated the post.

Martin

]]> By: Kabbo http://martincarstenbach.wordpress.com/2012/07/02/get-a-feel-for-enterprise-block-level-replication-using-drbd/#comment-2336 Wed, 04 Jul 2012 19:27:10 +0000 http://martincarstenbach.wordpress.com/?p=1405#comment-2336 Hi Martin,

As usual, I always read your very nice and up to date articles, bravo to you and keep up the good job of informing your fellow Database Analysts like myself. I just notice a very tiny “typo”, I believe. You might want look at this:

The domUs are Oracle Linux 6.2 with kernel 2.6.32-300.3.1.el6uek.x86_64, named ol62drbd1 and ol62drbd1. The second hostname should be ol62drbd2, as opposed to 1.

thanks,
Kabbo

]]> By: Noons http://martincarstenbach.wordpress.com/2012/07/02/get-a-feel-for-enterprise-block-level-replication-using-drbd/#comment-2317 Tue, 03 Jul 2012 04:47:14 +0000 http://martincarstenbach.wordpress.com/?p=1405#comment-2317 Martin, modern storage-level replication applied to databases uses a concept called “consistency groups” for synchronous replication that ensures some if not most of the disaster scenarios you described will not happen without awareness of a problem being there.
It is essential to learn the details of all that is possible nowadays in modern SAN h/w and sw before claiming that it can or cannot be done or is “dangerous” or not.
I do recall the horror stories of youre, let me assure you most of those scenarios are gone. It is a complex and wide field, believe me: I”ve been dabbling on it for the last 3 years and although I don’t profess to “know-it-all”, I do recognize it encompasses a lot more than I initally thought.
And there is more than just synchronous replication possible. Asynchronous is very viable and reliable method for things like s/w storage, archive logs, FRA, etcetc.
Particularly if preceeded by the caution of taking a snapshot on the remote site before effecting the replication – a la “before image”. And so on.
A lot can be said about this subject, thanks for taking the step to talk about it.

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