Database Reference
In-Depth Information
8.
Next, the active mirroring session will start and to verify look at the SQL Server error
log for the entries indicating the database mirroring is active. The entries will be
similar to the following:
11/21/2010 22:33:33,spid231s,Unknown,Database mirroring is active
with database 'AdventureWorks2008R2' as the principal copy. This
is an informational message only. No user action is required.
11/21/2010 22:33:33,spid231s,Unknown,Starting up database
'AdventureWorks2008R2'.
11/21/2010 22:34:13,Server,Unknown,SQL Server is now ready for
client connections. This is an informational message; no user
action is required.
11/21/2010 22:34:13,spid232s,Unknown,The Database Mirroring
protocol transport is now listening for connections.
11/21/2010 22:34:39,spid232s,Unknown,Server is listening on [
'any' <ipv4> 5022].
9. Now we have active mirroring, the next step is to monitor the mirroring topology using
the Database Mirroring Monitor tool from SSMS.
10. From SSMS, on the PRINCIPAL database, select Tasks | Launch Database Mirroring
Monitor (DMM).
11. The DMM tool includes the two server instances' status and specifies the log
after being moved from the
PRINCIPAL
to the
MIRROR
instance. This helps us to
determine if the
MIRROR
database is keeping up with the
PRINICPAL
database.
This completes the process of setting up the database mirroring and performance
enhancements using SQL Server 2008 R2.
How it works...
The three operating modes are High Safety/Protection, High Availability, and High
Performance. The database mirroring operating mode that was chosen here is high-availability
(
synchronous
mode
with
automatic
failover
) with a witness server.
The automatic page repair process is an asynchronous process which runs in the background,
and allows the mirrored database operation that requests an unreadable page to return the
error code condition causing a failure. The error codes are:
F
823
: ERROR_CRC, operating system value is 23
F
824
: Logical data errors, torn write, or bad page checksum
F
829
: indicates a page has been marked as restore pending
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