Posted by Roy Harvey (SQL Server MVP) on 09/29/07 21:10

The best place to ask this is microsoft.public.sqlserver.replication.

I am no replication expert, but your requirement sounds like it needs
Database Mirroring. I am guessing that a T1 would be a bit slow for
synchronous mode, also known as high-safety mode. "Under high-safety
mode, when a session begins, the mirror server synchronizes the mirror
database with the principal database as quickly as possible. Once the
databases are synchronized a committed transaction is committed on
both partners, at the cost of increased transaction latency."

That would leave asynchronous operation mode, also known as
high-performance mode. "The mirror server attempts to keep up with
the log records sent by the principal server. The mirror database
might lag somewhat behind the principal database, though, typically,
the gap between the databases is small. However, the gap can become
substantial if the principal server is under a heavy work load or the
system of the mirror server is over loaded."

"In high-performance mode, as soon as the principal server sends a log
record to the mirror server, the principal server sends a confirmation
to the client, without waiting for an acknowledgement from the mirror
server. This means that transactions commit without waiting for the
mirror server to write the log to disk. Such asynchronous operation
permits the principal server to run with minimum transaction latency,
at the risk of some potential data loss."

The quotes are straight from BOL.

Roy Harvey
Beacon Falls, CT

On Sat, 29 Sep 2007 13:38:48 -0400, "aleu@vp.pl" <aleu@vp.pl> wrote:

>Hi everybody,
>
>Could you please advise me what would be the best method to synchronize
>MSSQL data in the following scenario:
>
>SiteA (live site) ----- T1 link ----- SiteB (redundant site)
>
>Each site consists of web server and MSSQL 2005 server. SiteA is the
>site that my customers normally use when accessing my store. SiteB is
>the backup site to which customers will be directed, should something
>happen to Internet connectivity of siteA. When the failover occurs,
>client request are pointing to my redundant web servers within a minute
>(this happens automatically, as I am using the hosted DNS service). I
>was wondering, what is the best method of keeping the database at siteB
>up to date with all the transactions that took place at siteA? I do not
>want my customers to access the redundant database if it does not
>contain all the transactions. What would you advise?
>
>Thanks,
>AL

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