Hi:
I am looking for a Step-by-Step document for setting up and configuring of database mirroring if one is available. I have gone through BOL and found some related documentation but want to see if a step-by-step document is available. If so can any one please direct me to the resource.
Thank you
AK
Please look at the How-to section in the BOL.
http://msdn2.microsoft.com/en-us/library/ms175059.aspx
I'm interested in how Combining Log Shipping and Database Mirroring works when failover occurs.
From SQL BOL, it says:
"Topic: Database Mirroring and Log Shipping
...
To run in high-safety mode with automatic failover the mirroring
session is configured with an additional server instance known as the witness.
If the principal database is lost for any reason after the database is
synchronized and if the mirror server and witness can still communicate
with each other, automatic failover occurs. An automatic failover
causes mirror server to assume the principal role and bring its
database online as the principal database. For more information, see Automatic Failover
[ http://msdn2.microsoft.com/en-us/library/ms189590.aspx ] . If the log
shipping backup location is accessible to the new principal/primary
server, its backup jobs begin to ship log backups to that location. The
database mirroring synchronous mode guarantees that the log chain is
unaffected by a mirroring failover and that only valid log is restored.
The secondary servers continue to copy log backups without knowing that
a different server instance has become the primary server.
..."
Source: http://msdn2.microsoft.com/en-us/library/ms187016(d=printer).aspx
Could anyone tell me that how the database mirroring synchronous mode guarantees that the log chain is
unaffected by a mirroring failover and that only valid log is restored?
Let me elaborate the situation (if anything I said is incorrect, please correct me 
Here is the time line of the failover happens:
- tn-1 - tn - tf -- tn+1 > t
-> t: the time line.
tn: the moment that the log shipping backup job and copy job is done for the transaction log obtained between the time interval tn-1 and tn.
tf: the moment that mirroring failover occurs in the database mirroring session.
the time interval between each tn and tn-1 are constant, say h seconds, for all n are positive integers.
Here is the question that I want to ask:
In database mirroring synchronous mode, it guarantees that all the committed transaction from the moment tn to tf is copied to the mirror database. All the transaction log backup for log shipping are done on the original principal before the moment tf. After the mirroring failover occurs at the moment tf, how the log shipping mechanism guarantees that the transaction log between the interval tn and tn+1 that can be unaffected by a mirroring failover?
That's the point that I interested in.
Thanks a lot,
Terence
Hi Terence,
The key point to consider in the above scenario is the fact that the principal and mirror which participate in the mirroring relationship collaborate to similulate a single database which has had no failure. Starting from that observation, if there is a failover to the mirror, the next log backup will still capture all the transactions that have not yet been backed up on the principal, preserving the log chain. In your example above, the next transaction log backup from the mirror will contain all the log records past point tn.
Regards,
Matt Hollingsworth
Sr. Program Manager
Microsoft SQL Server
|||Hi Matt,Thanks a lot for your information.
It helps me a lot to understand Database Mirroring and Log Shipping. : )
Regards,
Terence
I'm interested in how Combining Log Shipping and Database Mirroring works when failover occurs.
From SQL BOL, it says:
"Topic: Database Mirroring and Log Shipping
...
To run in high-safety mode with automatic failover the mirroring
session is configured with an additional server instance known as the witness.
If the principal database is lost for any reason after the database is
synchronized and if the mirror server and witness can still communicate
with each other, automatic failover occurs. An automatic failover
causes mirror server to assume the principal role and bring its
database online as the principal database. For more information, see Automatic Failover
[ http://msdn2.microsoft.com/en-us/library/ms189590.aspx ] . If the log
shipping backup location is accessible to the new principal/primary
server, its backup jobs begin to ship log backups to that location. The
database mirroring synchronous mode guarantees that the log chain is
unaffected by a mirroring failover and that only valid log is restored.
The secondary servers continue to copy log backups without knowing that
a different server instance has become the primary server.
..."
Source: http://msdn2.microsoft.com/en-us/library/ms187016(d=printer).aspx
Could anyone tell me that how the database mirroring synchronous mode guarantees that the log chain is
unaffected by a mirroring failover and that only valid log is restored?
Let me elaborate the situation (if anything I said is incorrect, please correct me
Here is the time line of the failover happens:
- tn-1 - tn - tf -- tn+1 > t
-> t: the time line.
tn: the moment that the log shipping backup job and copy job is done for the transaction log obtained between the time interval tn-1 and tn.
tf: the moment that mirroring failover occurs in the database mirroring session.
the time interval between each tn and tn-1 are constant, say h seconds, for all n are positive integers.
Here is the question that I want to ask:
In database mirroring synchronous mode, it guarantees that all the committed transaction from the moment tn to tf is copied to the mirror database. All the transaction log backup for log shipping are done on the original principal before the moment tf. After the mirroring failover occurs at the moment tf, how the log shipping mechanism guarantees that the transaction log between the interval tn and tn+1 that can be unaffected by a mirroring failover?
That's the point that I interested in.
Thanks a lot,
Terence
Hi Terence,
The key point to consider in the above scenario is the fact that the principal and mirror which participate in the mirroring relationship collaborate to similulate a single database which has had no failure. Starting from that observation, if there is a failover to the mirror, the next log backup will still capture all the transactions that have not yet been backed up on the principal, preserving the log chain. In your example above, the next transaction log backup from the mirror will contain all the log records past point tn.
Regards,
Matt Hollingsworth
Sr. Program Manager
Microsoft SQL Server
|||Hi Matt,Thanks a lot for your information.
It helps me a lot to understand Database Mirroring and Log Shipping. : )
Regards,
Terence
Hi All,
I am trying to get Database mail running on SQL 2005. I have, very carefully, followed all the steps in BOL, and the Improved steps suggested in other posts on this forum (in particular
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=109885&SiteID=1
).
However when I try to send mail I get the error:
The mail could not be sent to the recipients because of the mail server failure.
(Sending Mail using Account 2 (2006-02-20T10:55:30).
Exception Message: Cannot send mails to mail server.
(Command not implemented. The server response was: Command not Supported).
)
Searching through other forums it appears that this is an SMTP issue of some sort:
(http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=112971&SiteID=1)
Anyone else seen this?
Unfortunately I didn't set up the server, so there may be required Windows components missing. When I first saw the error and tried to go through the steps in link 1 above, I discovered that SMTP was not on the box(!). It is up and running now, but I wonder if there is anything else missing.
Thanks, as always,
Richard R.
Richard,
I'm moving your thread to the Tools General forum. Hopefully they'll be able to answer.
