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  #41  
Old   
Geoff N. Hiten
 
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Default Re: Minimize failover time - 09-02-2008 , 09:06 AM






Reducing the failover time would result in lost transactions. A failover
event is much like a restart of the SQL Service. SQL Server must recover
each user database by rolling forward committed transactions and rolling
back uncommitted ones. There are some multi-tier architecture techniques
that can isolate the front end web service databases from the actual
back-end transactional ones, but those require significant application
changes.to implement.

--
Geoff N. Hiten
Principal SQL Infrastructure Consultant
Microsoft SQL Server MVP




"Pasquale" <Pasquale (AT) discussions (DOT) microsoft.com> wrote

Quote:
I have tried the failover by moving a resource group from one node to other
one.
The time registered refers to SQL Server resource recovering and not to
entire group recovering.
However, does exist a method to reduce the failover time (during a real
event or not) to avoid loss transactions? Thanks

"Tim Walsh" wrote:

Keep in mind what has to happen when a cluster fails over or is moved to
the
other node. The cluster has to recognize the failure or the move request.
The cluster then has to send SQL and the other resources shutdown signals
and then wait for all the resources to respond. If the resources don't
respond the cluster has to wait for the request to time-out before
killing
the resource. Once all the resources are off-line the cluster then has to
send start signals to the resources on the other node and again wait for
a
response. The resources most likely have to start up in a particular
order,
so the start signals have to wait for each resource in the particular
order
to start and respond before the next resource can be sent a start signal.
All of this signaling takes time, 15 to 20 seconds is actually pretty
good
response. I suspect you were testing the fail-over and this 15 to 20
seconds
isn't based upon an actual failure where timeouts will most likely be
encountered and a much slower response as a result.

This is what clusters do, they don't guarentee that you won't have a
service
interruption, just that the service interruption will be shorter then if
you
had to manually respond. Highly reliable and highly available are not the
same.





"Pasquale" <Pasquale (AT) discussions (DOT) microsoft.com> wrote in message
news:9C239FA3-ACC2-476B-AA1F-2EA208D056F9 (AT) microsoft (DOT) com...
I have a two node cluster (active/active).
When I try the failover with the cluster administrator tool I have seen
that
it occurs 15-20 seconds to recover the SQL Server resource.
Is it possible to decrement the failover time for the SQL Server
resource?
How?
Thanks





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  #42  
Old   
Edwin vMierlo [MVP]
 
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Default Re: Minimize failover time - 09-02-2008 , 09:52 AM







"Geoff N. Hiten" <SQLCraftsman (AT) gmail (DOT) com> wrote

Quote:
Reducing the failover time would result in lost transactions. A failover
event is much like a restart of the SQL Service. SQL Server must recover
each user database by rolling forward committed transactions and rolling
back uncommitted ones. There are some multi-tier architecture techniques
that can isolate the front end web service databases from the actual
back-end transactional ones, but those require significant application
changes.to implement.

absolutely,
And, although mentioned before,
I believe a 15-20 second is not all that bad.




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  #43  
Old   
Edwin vMierlo [MVP]
 
Posts: n/a

Default Re: Minimize failover time - 09-02-2008 , 09:52 AM




"Geoff N. Hiten" <SQLCraftsman (AT) gmail (DOT) com> wrote

Quote:
Reducing the failover time would result in lost transactions. A failover
event is much like a restart of the SQL Service. SQL Server must recover
each user database by rolling forward committed transactions and rolling
back uncommitted ones. There are some multi-tier architecture techniques
that can isolate the front end web service databases from the actual
back-end transactional ones, but those require significant application
changes.to implement.

absolutely,
And, although mentioned before,
I believe a 15-20 second is not all that bad.




Reply With Quote
  #44  
Old   
Edwin vMierlo [MVP]
 
Posts: n/a

Default Re: Minimize failover time - 09-02-2008 , 09:52 AM




"Geoff N. Hiten" <SQLCraftsman (AT) gmail (DOT) com> wrote

Quote:
Reducing the failover time would result in lost transactions. A failover
event is much like a restart of the SQL Service. SQL Server must recover
each user database by rolling forward committed transactions and rolling
back uncommitted ones. There are some multi-tier architecture techniques
that can isolate the front end web service databases from the actual
back-end transactional ones, but those require significant application
changes.to implement.

absolutely,
And, although mentioned before,
I believe a 15-20 second is not all that bad.




Reply With Quote
  #45  
Old   
Edwin vMierlo [MVP]
 
Posts: n/a

Default Re: Minimize failover time - 09-02-2008 , 09:52 AM




"Geoff N. Hiten" <SQLCraftsman (AT) gmail (DOT) com> wrote

Quote:
Reducing the failover time would result in lost transactions. A failover
event is much like a restart of the SQL Service. SQL Server must recover
each user database by rolling forward committed transactions and rolling
back uncommitted ones. There are some multi-tier architecture techniques
that can isolate the front end web service databases from the actual
back-end transactional ones, but those require significant application
changes.to implement.

absolutely,
And, although mentioned before,
I believe a 15-20 second is not all that bad.




Reply With Quote
  #46  
Old   
Edwin vMierlo [MVP]
 
Posts: n/a

Default Re: Minimize failover time - 09-02-2008 , 09:52 AM




"Geoff N. Hiten" <SQLCraftsman (AT) gmail (DOT) com> wrote

Quote:
Reducing the failover time would result in lost transactions. A failover
event is much like a restart of the SQL Service. SQL Server must recover
each user database by rolling forward committed transactions and rolling
back uncommitted ones. There are some multi-tier architecture techniques
that can isolate the front end web service databases from the actual
back-end transactional ones, but those require significant application
changes.to implement.

absolutely,
And, although mentioned before,
I believe a 15-20 second is not all that bad.




Reply With Quote
  #47  
Old   
Edwin vMierlo [MVP]
 
Posts: n/a

Default Re: Minimize failover time - 09-02-2008 , 09:52 AM




"Geoff N. Hiten" <SQLCraftsman (AT) gmail (DOT) com> wrote

Quote:
Reducing the failover time would result in lost transactions. A failover
event is much like a restart of the SQL Service. SQL Server must recover
each user database by rolling forward committed transactions and rolling
back uncommitted ones. There are some multi-tier architecture techniques
that can isolate the front end web service databases from the actual
back-end transactional ones, but those require significant application
changes.to implement.

absolutely,
And, although mentioned before,
I believe a 15-20 second is not all that bad.




Reply With Quote
  #48  
Old   
Edwin vMierlo [MVP]
 
Posts: n/a

Default Re: Minimize failover time - 09-02-2008 , 09:52 AM




"Geoff N. Hiten" <SQLCraftsman (AT) gmail (DOT) com> wrote

Quote:
Reducing the failover time would result in lost transactions. A failover
event is much like a restart of the SQL Service. SQL Server must recover
each user database by rolling forward committed transactions and rolling
back uncommitted ones. There are some multi-tier architecture techniques
that can isolate the front end web service databases from the actual
back-end transactional ones, but those require significant application
changes.to implement.

absolutely,
And, although mentioned before,
I believe a 15-20 second is not all that bad.




Reply With Quote
  #49  
Old   
Edwin vMierlo [MVP]
 
Posts: n/a

Default Re: Minimize failover time - 09-02-2008 , 09:52 AM




"Geoff N. Hiten" <SQLCraftsman (AT) gmail (DOT) com> wrote

Quote:
Reducing the failover time would result in lost transactions. A failover
event is much like a restart of the SQL Service. SQL Server must recover
each user database by rolling forward committed transactions and rolling
back uncommitted ones. There are some multi-tier architecture techniques
that can isolate the front end web service databases from the actual
back-end transactional ones, but those require significant application
changes.to implement.

absolutely,
And, although mentioned before,
I believe a 15-20 second is not all that bad.




Reply With Quote
  #50  
Old   
Edwin vMierlo [MVP]
 
Posts: n/a

Default Re: Minimize failover time - 09-02-2008 , 09:52 AM




"Geoff N. Hiten" <SQLCraftsman (AT) gmail (DOT) com> wrote

Quote:
Reducing the failover time would result in lost transactions. A failover
event is much like a restart of the SQL Service. SQL Server must recover
each user database by rolling forward committed transactions and rolling
back uncommitted ones. There are some multi-tier architecture techniques
that can isolate the front end web service databases from the actual
back-end transactional ones, but those require significant application
changes.to implement.

absolutely,
And, although mentioned before,
I believe a 15-20 second is not all that bad.




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