clustering Vs Mirroing Vs Logshipingf Vs replication

  • Hi All,

    We are planing to setup HA for our SQL Server , I m quite confused which to use. Could you please suggest me a comparission featurewise on the above componenets.

    Looking forward witrh your input.

    Cheers,

    Got an idea..share it !!

    DBA_Vishal

  • need to know a bit more about your requirements first, as well as answers to the following

    Network connection between sites

    Hardware available

    DR databases to be readable or offline

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    "Ya can't make an omelette without breaking just a few eggs" 😉

  • I'm gonna be blunt here, so don't get offended but DO listen. HA is a CRITICAL part of a business' ability to function. If you screw it up you could lose your company, or fail to deliver healthcare to critically sick patients and have them die, or fail to produce electricity from the power plant, etc, etc. It is that simple. And to have any hope at all of getting it right you simply MUST have training, experience, knowledge that you and presumably no one else at your company has or you wouldn't be writing a forum post like you did. That means you need to bring in such assistance for this project. Over and over and over I have seen clients (and forum posters) try to do this after a few forum posts or reading a few blog posts, etc. and I have never seen it go well. But I HAVE seen companies go out of business because their HA or DR was messed up.

    Best,
    Kevin G. Boles
    SQL Server Consultant
    SQL MVP 2007-2012
    TheSQLGuru on googles mail service

  • To provide more context, on the HA setup we are looking we have two DC one we are planing to be HA and oter will be DR.

    I have to present my VP, with a plan what is the best approch for HA and DR. SQL Server has got many good componenets like Log shipping, DB mirroing, cluster and ALWAYS oN . I need to compare these and propose the best one.

    Cheers,

    Got an idea..share it !!

    DBA_Vishal

  • To be honest, recommend that they get someone experienced with HA/DR in to do the design at the very least.

    Otherwise, start with this:http://www.amazon.com/Server-2005-Availability-Experts-Voice/dp/159059780X/

    and tell your boss that you'll need a few months and some test hardware to play around on.

    Gail Shaw
    Microsoft Certified Master: SQL Server, MVP, M.Sc (Comp Sci)
    SQL In The Wild: Discussions on DB performance with occasional diversions into recoverability

    We walk in the dark places no others will enter
    We stand on the bridge and no one may pass
  • vkundar (8/6/2014)


    To provide more context, on the HA setup we are looking we have two DC one we are planing to be HA and oter will be DR.

    I have to present my VP, with a plan what is the best approch for HA and DR. SQL Server has got many good componenets like Log shipping, DB mirroing, cluster and ALWAYS oN . I need to compare these and propose the best one.

    Doesn't provide anywhere near enough, this is why you need to hire an experienced consultant to draw a plan and advise on the best route possible.

    -----------------------------------------------------------------------------------------------------------

    "Ya can't make an omelette without breaking just a few eggs" 😉

  • Before you rush out and hire a consultant or try to do this yourself, you have to come up with detailed real requirements for what your HA/DR solution is supposed to accomplish.

    So go to your VP and sit down with him and other stake holder in whatever runs on your db systems and hammer out the requirements.

    Only once you have that can you begin to try to figure out what the appropriate/best solution is.

    HA isn't something you stand up just because your VP thinks it is what all the cool IT mangers are doing these days.

  • A note on HA/DR solutions, and one that's not always considered, so bear with me. Yes, I'm playing Devil's Advocate.

    The most likely need for HA/DR is power outage and/or fire in the building. Let's exclude statewide catastrophes or invasions from Mars.

    If your building has no power (think line cut by a backhoe right outside), do your employees need to work? Do you have VPN capabilities for the majority, if not all, of your staff to login to the apps they'd need to do their jobs? If not, then those don't need HA/DR, they just need to make sure your backups get offsite in case of fire.

    Do your customers come to you online and do the majority of their purchasing/sales/etc without any human interaction? If so, then you need to setup your HA/DR so that the DNS at your IP knows to switch over in case of failure or you need a plan.

    There's a TON of things to be concerned about with HA/DR, and it's not just 'is my data protected', though that's a nice to have secondary output of proper setup. Disaster Recovery is different than High Availability, and combining the two is an animal in it's own right that you need to be sure you're wisely using resources and time to construct for something that you could actually use.

    I know many companies that if the building burns down... it doesn't matter what the hell happened to the data as long as the accounting database is backed up somewhere to answer creditors. That company is GONE. Just gone. They can't recover from the loss of product in the warehouse, machinery on the floor, etc. Part of the process is determining what disasters they're actually feasible to recover from.

    Example: Your VPN goes through Site A, which has a T1 connecting to Site B where you have all your servers, apps, etc. Your HADR is at Site C... which only has a connection to Site B. Guess what... it's worthless. Your VPN can't get to Site C. I was recently staring at this setup so I can't go into more details, NDAs, but it illustrates the ten thousand things you need to think about for setting this up.


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