Mirror or Log shipping?

  • We are planning the implementation of a new off the shelf CRM system. The requirement is to have the live system on Server A, which will be the only place that data is updated. The data from Server A is to be replicated to Server B. Server B will be used for reporting. Both servers are on ther same LAN, and will be running SQL Server 2008 Standard. The requirement for how often Server B is updated is vague; it seems to be 'daily or better'.

    I was thinking about snapshots at that point. An external adviser suggested log shipping.

    The discussion then turned to disaster recovery. True High Availability is not required, and clustering has been ruled out. We want to use Server B for disaster recovery, in case Server A fails. In the event of a serious fault on Server A we would have the option run with just Server B for both data updates and reporting. To me this means that we need the data on B to be more up to date.

    I was going to suggest we use Mirroring instead of Log shipping. I would just like to be reassured that I am not missing any obvious 'gotchas'. I recently read about issues with mirroring and the new filestream in 2008, but I doubt that will be an issue with this system at this time.

    Any advice please - does mirroring seem like a better option than log shipping in this scenario? If there are any obvious pitfalls with this idea then your advice would be much appreciated.

    Thanks

    Paul

  • AS i can see you are using Standard Edition, you can do mirroring but the database will be on restore more and you cant read data from database, so in this case you have to use Enterprise Edition, where you can create a database snapshot, so you can use for both DR and reports.

    On the other hand, if you are prepared to loss some data on your DR plan, then logshipping is the option , which i am using now for the same purpose.

    Please note, i am new to mirroring, please let me know if there is a way to access data from database that is been mirrored ( Server B).

  • Thanks for the reply.

    I have a bit of time, so I will set up a couple of virtual dev servers and experiment. Sounds like log shipping may be the way to go, so I'll try that out.

  • I haven't used log shipping since sql 2000 - but even though you could leave the database in standby mode (which allows read only access), when the log is restored it has to kill all the existing connections to get exclusive access to restore the log. If you are using log shipping with a 15 minute window, that means every 15 minutes, all the connections are severed... even those in the middle of a query to build a report. It still works ok if you don't mind redoing the query (or program the client to do that for you), but it can get annoying.

    I don't know if it changed in 2005, so you get what you pay for with this post ;-), but it is something to think about and test.

    Good Luck!

    Chad

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