SQL 2012 :: AlwaysON Linked Servers Failover
Jan 27, 2015
So I have 2 servers S1 & S2.
Database Group 1 = L1 with Primary S1 and Secondary S2
Database Group 2 = L2 with Primary S2 and Secondary S1
For 99% of the time the 2 groups of databases are not related. For the 1 procedure that does move data from L1 to L2 something like
Update L2.DB.Owner.Table
set flag = 1
Whare a = 0
On S1 I have a linkedServer with connection to L2.
If I have a failover I cannot have L2 on S2 as they are essentially the same server.
How to I use the 2 groups hand in hand.
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Mar 28, 2014
What happens when an automatic failover occurs, in a two server AlwaysOn Availability Group configuration, where the secondary replica is configured as read-only?
Will it only allow read-only connections, or will it become read-write and can accept INSERT, UPDATES and DELETES when assigned the new role as Primary?
Is it correct that adding a third server/node, that just acts as passive and should be used for automatic failover, to support true HADR, would NOT need another license .. and that licenses would only be required for the previous Primary and Secondary (Read-Only) replicas?
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Dec 10, 2014
I have setup SQL AlwaysOn between primary and DR data centers. Here is the setup:
Primary data center: Server1 (Primary), Server2 (Sync Commit Secondary), Server3 (ASync Commit Secondary)
DR data center: Server4 (ASync Commit Secondary)
Data synchronization and manual failover works fine. But, sometimes, the AlwaysOn cluster automatically fails over to Sync Commit Secondary on Primary data center. Here is the error message from Failover Cluster Manager->Cluster Events:
"Cluster has missed two consecutive heartbeats for the local endpoint xx.xx.xx.yy:~3343~ connected to remote endpoint xx.xx.xx.zz:~3343~"
"Cluster has lost the UDP connection from local endpoint xx.xx.xx.yy:~3343~ connected to remote endpoint xx.xx.xx.zz:~3343~"
I had our network engineer check all connections multiple times and he confirmed everything is fine. But he was also able to confirm (using monitoring tools) that right at the time of a failover, there is almost 2GB worth of traffic going from Primary Server to DR server. That happens every time. I had checked the times of all failovers and there is no job or process occuring that will produce 2GB worth of data. Also, this happens regardless of which server is primary.
Even though the failover works fine, this unexpected automatic failover due to missed heartbeats are occurring often (2-3 times a month).
Here is the list of errors from the Cluster Validation Report:
Under Network Section, I see the following error messages in Red:
Validate Network Communication
Network interfaces Server4 (DR) - SAN_Team and Server1 (Primary) - SAN_Team - VLAN 20 are on the same cluster network, yet address xx.xx.xx.pp is not reachable from xx.xx.xx.yy using UDP on port 3343.
Network interfaces Server4 (DR) - SAN_Team and Server2 (Secondary) - SAN_Team - VLAN 20 are on the same cluster network, yet address xx.xx.xx.qq is not reachable from xx.xx.xx.yy using UDP on port 3343.
[Code] ....
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Apr 3, 2014
I'm looking for a solution to have cross data center automatic failover in the event of a data center loss for highly critical databases. I would like to have local HA and also automatic failover to the DR site. This does not seem possible with AlwaysOn.
Is my only option for automatic cross data center failover to build a node in one data center and a node in the other data center with a node/FS at a third data center in order to maintain quorum? I'd like to have local HA in the mix but that doesn't seem possible.What pattern for the highest data security and also availability?
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Jun 16, 2014
If there is a history kept somewhere of failover events of a database in an AO group? I have 2 replicas with automatic failover and I'm looking for a history of failovers.
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Oct 6, 2014
We are implementing a multi-site (Windows Server Failover Cluster) WSFC to enable Always On between our primary and DR site. We are not going to use SQL clustered instances. We are not planning to use shared disks. Each node is running a standalone instance of SQL 2012.
I have successfully configured a 3 node multi-site Windows failover cluster with no shared storage. For quorum, I have defined a File Share Witness (FSW). The FSW has voting rights and is in the DR site. The setup looks like this –
WSFC –
•Node A – Site #1 (voting right = 1)
•Node B – Site #1 (voting right = 1)
•Node C – Site #2 (voting right = 0)
•FSW – Site #2 (voting right = 1)
Again - There are no shared disks in our setup. We are not going to use SQL clustered instance. We are going to use Always On with these 3 nodes.
SQL Always On –
•Node A – Site #1 (Primary Replica)
•Node B – Site #1 (Readable Secondary)
•Node C – Site #2 (Readable Secondary)
All the setup including the “availability group” works properly under this setup. However, a failover to site #2 under DR situation is not working and I know why but don’t know what needs to be done to fix the problem.
The following works fine –
•Automatic failover between nodes A and B (same site – site #1)
•Forced failover to node C in site #2 provided at least one of the nodes in site #1 is up (non – DR situation) - this will ensure the cluster is up
The following is not working –
•Forced failover to node C in site #3 when both nodes in site #1 are lost (true DR situation) – This is because the cluster is not up at this point.
I know I have to bring the cluster up somehow and I have not been able to do so by restarting the cluster service.
I tried to run the command to start cluster service.
Question –
How can I FORCE the cluster to come up in Site #2 on node C when it has no voting rights?
I have always worked with even number of nodes and shared disks with traditional clustering. I am not sure what needs to be done in this scenario with 3 nodes and a FSW.
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Sep 30, 2015
How can we find the cluster failover count in always on ?
As my AG is configured as synchronous mode , AG went offline and we manually restarted the AG service when we check the properties on AG role they r in default setting ?
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Oct 27, 2015
An automatic failover set exists. This set consists of a primary replica and a secondary replica (the automatic failover target) that are both configured for synchronous-commit mode and set to AUTOMATIC failover.Configured the both AG Group database automatic failover and synchronous-commit mode.But automatic Failover failed also Cluster service not started automatically at Node2. It got connected through AO Listerner after starting Node1. As below SQL Error log during shutdown Node1
Date,Source,Severity,Message
10/27/2015 10:44:20,spid37s,Unknown,AlwaysOn Availability Groups: Waiting for local Windows Server Failover Clustering node to come online. This is an informational message only. No user action is required.
10/27/2015 10:44:20,spid37s,Unknown,AlwaysOn Availability Groups: Local Windows Server Failover Clustering node started.
[code]....
what need to be change existing AO configuration?
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Oct 29, 2015
1. Once fail over to secondary replica, what will happen to connected session in primary node? can the session fail over to secondary seamlessly or need to re-login. what happen committed transactions which has not write to disk.
2. Assume I have always on cluster with three nodes, if primary fails, how second node make write/ read mode.
3. after fail over done to 2nd secondary node what mode in production(readonly or read write).
4. how to rollback to production primary ,will change data in secondary will get updated in primary.
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Oct 29, 2015
1. In alwaysON fail over cluster, Once fail over to secondary replica, what will happen to connected session in primary node? can the session fail over to secondary seamlessly or need to re-login. what happen committed transactions which has not write to disk.
2. Assume I have always on cluster with three nodes, if primary fails, how second node make write/ read mode.
3. After fail over done to 2nd secondary node what mode in production(readonly or read write).
4. How to rollback to production primary ,will change data in secondary will get updated in primary.
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Sep 18, 2014
I know now that AlwaysOn feature HAS to be installed/configured on a Windows Clustering environment, BUT the secondary replicas, like the Disaster recovery replica residing in a different Data Center HAS to be also in a Windows Clustering environment or can it reside on a SINGLE SQL Server INSTANCE?.
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Jul 22, 2014
it is possible to create Linked server with Failover partner option. I can query when primary server and getting the error when I set the DB Fail over. I have tried with following script and also gone through different sources, but failed. Please see the script and error below.
EXEC master.dbo.sp_addlinkedserver
@server = N'MIRRORLink',
@srvproduct=N'',
@provider=N'SQLOLEDB',
@provstr=N'Server=primary;FailoverPartner=mirror;network=dbmssocn;',
[code].....
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Dec 16, 2014
I have a HA Listener which is visible and can be connected to, it has a read only secondary on a different subnet so when connecting to it we use the applicationintent = readonly and multisubnetfailover = true.
Trying to connect it as a linked server is giving me problems. I tried putting the extra info into the provider string but keep getting the failure to initialise error. I am trying to link SQL2012 to a 2012 HA group but will also need to connect from a sql2008 server as well
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Jun 7, 2015
I Config Ha-Alwayson on 2 test servers . In addition, was defined a listener for them.i can connect to them from the listener and in directly. I did manual Failover and it worked.However all connection to all servers (primary and secondary and listener) was breaked. I expected my connection To The listener, be stable. But How can I test the Auto failover mechanism? I run this scenario :
1- I filled all free space from the primary server else a bit.
2- And run on it a Huge Update to fill remain free space.
3- MeanWhile I Run an insert command into listener IP. (in a while Loop)
I expected :
>>> After run update or in middle of it , The primary server face to a problem. (Full Log file). And This was happened.
>>> After I expected The Failover act and change Primary And Secondary.And My insert commands Continues without Break Or Continue On new server After some Seconds
But It didn't Happend.Both Of 2 Command are stoped !!!!! And auto failover didnt act. I tryed To create a manual fail on primary server . I Tried to Offline the main database in primary server.
Then
1- What is the meaning Of fail that Auto failover act about it ?
2- In which scenario I can Test It ?
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Jun 30, 2015
I have a 3 node 2014 AlwaysOn setup. The primary and secondary are set for automatic failover. The third node, of course, is manual (until 2016). The 2 nodes with are automatic are sitting in one datacenter, the third is in another. If the first datacenter was to go down, I would manually have to failover to the third node? What's the normal process here for having two datacenters and ensuring the availability group is always available?
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Jun 30, 2015
we have to build high availability SQL 2012 cluster for VDI and we have two options. One option is to build a server cluster with combination of failover and mirroring and other option is to build failover cluster with AlwaysOn.We are not sure which option to chose. We have contacted Microsoft support to provide us some documents and instructions for failovermirroring combination but they have send us instructions for AlwaysOn option.
What would be best way to build high availability cluster for VDI? Also, since first option is very complicated.
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Jul 27, 2015
Is there any single TSQL query which provides below info.When did my AlwaysOn Availability group failed over and from which node it failed to which new node(i.e. replica)?
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May 22, 2015
I'm getting an error adding Replica to SQL AlwaysOn failover cluster in the new availability group wizard. When I enter the name of the target node (secondary replica) server and press connect, I get the following:
A network-related or instance-specific error occurred while establishing a connection to SQL Server.
The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server) (Microsoft SQL Server, Error: 2) The system cannot fine the file specified
The SQL Browser service is up and running on the target. I am using an Azure VM for my SQL instance. This cluster spans geographies from our on-premise site to Azure via a VPN. This is a multi-subnet cluster. I'm attempting to create a new AG from the primary replica node and the target is a node on Azure called SSASNodeAz03.
[URL]
Full error:
Connect to Server
Cannot connect to ssasnodeaz03
Additional information: A network-related or instance-specific error occurred while establishing a connection to SQL Server.
The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server) (Microsoft SQL Server, Error: 2) The system cannot fine the file specified
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Oct 23, 2015
We had to failover our primary db server for maintenance to our secondary replica. The primary was rebooted during maintenance. We failed back after the maintenance and one of the databases is not synchronizing.
I checked sys.dm_hadr_database_replica_states, and it is showing that it is INITIALIZING.
It has been in this state for more than 45 mins now. The last_sent_time, last_received_time, last_hardened_time and last-redone_time are all stuck with a time stamp 45 mins ago.
They haven't changed. How do i resume this database and bring it back in sync?
I tried suspending and resuming the data movement, but hasn't worked.
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Aug 25, 2015
I am running SQL 2014 2-node AlwaysON Availability groups, Enterprise Edition in our environment and 5 databases are part of AG.
Question is, sometimes AG is getting failed over to node2 but always our preferred node is node1 due to some business needs otherwise some of our jobs will fail.
So, what I looking for is, a sql script which can handle a situation wherein, for some reason, AG is failed over to node2, it should be able to detect if node1 is back online or not and if so, it should fail back to node1. How to do this using tsql query or stored proc or sql agent job ?
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May 13, 2008
Hi all,
Is it possible to setup auto-autofailower on 2 servers? Do i need to setup a witness on each server or what?
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Aug 17, 2015
We have a requirement to build SQL environment which will give us local high availability and disaster recovery to second site. We have two sites- Site A & Site B. We are planning to have two nodes at Site A and 2 nodes at Site B. All four nodes will be part of same Windows failover cluster. We will build two SQL Cluster, InstanceA will be clustered between the nodes at Site A Server and InstanceB will be clustered between the nodes at Site B, we will enable Always On Between the InstanceA and InstanceB and will be primary owner where data will be written on InstanceA and will be replicated to InstaceB. URL....Now we want we will have instanceC on the Site B and data will be writen from the application available on Site B, will be replicated to the instance on the Site A as replica.
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Dec 9, 2006
I have setup a database mirroring session with witness - MachineA is the principal, MachineB is the mirror, and MachineC is the witness. Each SQL Server instance is hosted on its own machine. The mirroring is working correctly. If I submit data to the database on MachineA, and then unplug the network cable on MachineA, MachineB automatically becomes the principal, and I can see the data that I originally submitted to MachineA on MachineB. All the settings are showing correctly in Management Studio.
My issue is with the SQL Native Client and a front-end application that needs to make use of this database. I have setup my front-end application to use the ODBC client and specified the failover server in both the ODBC setup and the connection string. Here is the connection string that I am using :
Provider=ODBC;Database=master;DSN=MachineA;Failover Partner=MachineB;
Everything works perfectly on my front-end application when MachineA is the principal. If I unplug the network cable on MachineA, MachineB becomes the principal, and the failover occurs correctly on the database side. The problem is that my front-end application is not able to query the database on MachineB.
BUT - if I plug the network cable back in on MachineA (making the database on MachineA the mirror), the front-end application now works and can access the principal database on MachineB. I wrote a quick tester application to verify what I am seeing, and I am convinced that this is what is happening. The mirroring is working perfectly, and everything is setup correctly. The SQL Native Client is setup correctly. The problem is that the automatic failover to MachineB that is built into the SQL Native Client only works if both servers are plugged in.
In this scenario, when I plug both servers in, I know that the front-end app is definitely pulling from MachineB (since the mirror database on MachineA is in recovery mode, it's unavailable, and the front-end app displays the server that it is pulling data from).
Am I using an out-dated SQL Native Client? The version number displayed in the ODBC configuration page is 2005.90.2047.00, and is dated 4/14/2006. Has anyone experienced this issue? I'm guessing that it's a problem in the SQL Native client, since the mirroring really seems to be working correctly.
Thanks,
Bill
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Sep 18, 2006
We have a mirror setup, with a third server that needs to be linked to this mirrored setup. The link server setup only allows you to specify the primary server. How will the linked server setup know what the secondary server is? Thanks
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Sep 18, 2006
We have a mirrored db setup, with a third server that needs to be linked to this mirrored setup as a linked server. The link server setup only allows you to specify the primary server. How will the linked server setup know what the secondary server is? Thanks
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Feb 22, 2007
Hi all,
The following query that uses a linked server is giving me the error message below after I initiate a failover (ALTER DATABASE Northwind SET PARTNER FAILOVER). I have SQL Server 2005 SP2. I think that without the service pack there is another error too.
The query is run from a database other than northwind of course.
select * from DualLink.northwind.dbo.Test1
Please note that:
without a failover it works perfectly
it always work if I try to run it a second time - only the first time it fails.
it fails the first time for each of the open connections. A new connection that was open after the failover will work fine.
A transport-level error has occurred when sending the request to the server. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.)
A transport-level error has occurred when sending the request to the server. (provider: Shared Memory Provider, error: 0 - No process is on the other end of the pipe.)
The linked server is defined as
EXEC master.
dbo.sp_addlinkedserver
@server = N'DualLink',
@srvproduct=N'',
@provider=N'SQLOLEDB',
@catalog=N'northwind',
@provstr=N'Server=(local);FailoverPartner=MyIPAddr;'
EXEC master.dbo.sp_addlinkedsrvlogin
@rmtsrvname = 'DualLink',
@useself = false,
@locallogin = 'sa',
@rmtuser = 'sa',
@rmtpassword = 'MyPwd'
Thanks,
Avi
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Feb 15, 2008
We are using SQL Server 2005 (9.0.3054 on Windows 2003 RC2 SP2 with clustering two instances. We are running an instance on both boxes.
I have 2 linked servers to the same server on the first box (SQL1C) that use different SQL Logins to connect to the same box but to different databases. One uses the name of the server and one uses the name of the server with a 2 at the end of it. (servername and servername2). The second linked server was added recently and is used very frequently by the new application. The other thing is there is a server with the name servername2. They are SQL boxes but I am not sure what version or what they are running on. If it turns out to be important, I will ask.
Here's what is happening:
When we fail over to the second box, up until recently, we had no problems. All linked servers worked well. But since we have added this new linked server, when we fail over, the linked server no longer works and we get an error like from the Cold Fusion application:
[Macromedia][SQLServer JDBC Driver][SQLServer]TCP Provider: An existing connection was forcibly closed by the remote host.
I got a similar error in EMS, but did not copy it to save it. Since this is a production server, I can't really just try things.
We checked to make sure all IPs from box1 and box2 are allowed access to the server and they are not using IP blocking for inside the university domain.
There are no errors in the SQL Logs. I checked the application logs and found no errors for the linked server. The only error I could find and I didn't think it was related but I will include it was this:
Closed event notification conversation endpoint with handle '{4F54167A-F3D0-DC11-97FE-000E0CB2D7CA}', due to the following error: '<?xml version="1.0"?><Error xmlns="http://schemas.microsoft.com/SQL/ServiceBroker/Error"><Code>-8470</Code><Description>Remote service has been dropped.</Description></Error>'.
Any ideas? One of our pplications goes down when the cluster fails over now. Help PLEASE!
Thanks,
Linda
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Aug 18, 2014
How to find the pending transactions to be applied on secondary in Always On? Can i get those details from dashboard?
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Oct 22, 2014
We are looking to setup an AlwaysOn A/G between two SQL instances across two SQL clusters - one cluster has two nodes the other has three nodes.
Is this possible using WSFC? Does the A/G wizard just handle this?
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May 13, 2013
I'm setting up my first pair of Sql 2012 servers using AlwaysOn. I set up backups to run on the primary and I understand that you can set up backups to run on both the primary and secondary servers but the secondary will fail. Is there a way I can stop the secondary server from sending out error messages about failed backups? Is it possible to script it so that the server looks at whether it's primary or secondary and turns on or off alerts based on that?
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Mar 13, 2014
I am trying to build the 2 node 2 clusters with the AlwaysOn.
Here isthe landscape.
2 nodes PROD failover cluster (running once instance)
2 nodes DR failover cluster (running 2 instances - DR and PRE-PROD)
Both clusters are in different geographies.
PRE-PROD can be editable. So out of scope of Always On.
One instance on PROD -> DR of the other box. [Want to achive thru AlwaysON]
Now my Question:
1) Do i need to have all the 4 nodes in same failover cluster group? If yes, then this would become MultiSubnet cluster Or Is there any way those 2 diffrerent failover clusters (one DR and one PROD) can be part of AlwaysOn.
2) Can i use the clustered disks as in the above landscape for always on?
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Apr 11, 2014
We have 2 SQL 2012 servers. Our application has 2 databases. We are creating an AlwaysOn cluster. Is it good to create 2 AlwaysOn clusters to have 1 database primary on one of the servers and the other database primary on the other server?
I have been asked if it is possible to have one database running on one server and the other database on the other server. Is this possible without creating 2 separate AlwaysOn clusters?
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Apr 14, 2014
While configuring SQL Server 2012 Cluster with Always on, why do we need two secondary replicas.
The attached link will describe the actual query. [URL] ....
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