[freetds] SQL Server 2005 Mirroring
Brian Bruns
brian.bruns at gmail.com
Tue Apr 17 07:29:58 EDT 2007
>From my own experience, most clustering arrangements involve IP address
takeover, so that one box detects a failure with its partner and then
proceeds to take over the resources (disk, processes, ip addresses). This
is preferable to DNS switch over due to the propagation delay of DNS.
The problem with bolting this into FreeTDS (or any client package) is the
client can't determine if the server is down or not. So, if you had a
momentary network glitch, for instance, you generally don't want your
clients flipping over to your secondary when the primary server is alive and
well.
The primary and secondary servers can maintain a heartbeat via serial cable
or private ethernet and know when to do the right thing.
Note, I'm a unix guy, so much of this is from AIX or linux experience. I
believe Microsoft calls their equivalent software "MSCS"
Brian
2007/4/17, Beth Woods <agentbeckett186 at yahoo.com>:
>
> Thank you for the quick reply. That was very helpful, even though it
> wasn't the answer I was hoping for :)
>
> Thanks,
> Beth
>
> ----- Original Message ----
> From: James K. Lowden <jklowden at freetds.org>
> To: FreeTDS Development Group <freetds at lists.ibiblio.org>
> Sent: Monday, April 16, 2007 10:31:59 PM
> Subject: Re: [freetds] SQL Server 2005 Mirroring
>
> Beth Woods wrote:
> >
> > Our servers are mirrored so that if
> > the primary goes down the mirror will automatically handle any new
> > connections. How can I configure this with the freetds driver? What I
> > basically need is an alternate server. I did not see that as an option
> > for the configuration file.
>
> Welcome to the project, Beth.
>
> FreeTDS doesn't do any kind of failover. It follows DNS. In my work
> environment, we have a CNAME DNS record that points to the primary. On
> failure, that entry is changed to point to the secondary.
>
> I think this kind of arrangement is fairly common.
>
> HTH.
>
> --jkl
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