SQL 2012 :: Failover On 2 Servers AlwaysOn AG With Read-only Secondary Replica
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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May 21, 2013
I have an AlwaysOn Availability group configured between 2 nodes (Synchronous)
Automatic failover was working fine until recently
I can failover between the nodes manually but automatic failover doesn't seem to be working. In my earlier test, I would shut down the SQL Service on the primary and within seconds, the secondary replica would take over. Recently I have performed the same test and the secondary replica enters the resolving state and the DB in unavailable.
I have tried everything here: [URL] ....
The only change I made was changing the availability mode from Synchronous to Asynchronous - Could that be the cause?
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Apr 11, 2014
Looking for info on ole/requirement of primary and secondary replica under SQL Server 2012 AlwaysOn.
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Aug 6, 2014
I was working on a job to send me info each morning about database file free space and was noticing some odd things when looking at the log file VLFs for one of my databases in an AlwaysOn availability group.When I run DBCC LOGINFO on the secondary replica for this database, I get what I expect and most VLFs have a status of 0 (indicating the VLFs are reusable or unused). When I run DBCC LOGINFO on the primary replica, all of the VLFs have a status of 2 (active or recoverable).
Since log backups on the secondary replica in AlwaysOn still truncate the log in the primary replica, I would expect that the VLFs in the primary replica would also be mostly in a reusable or unused state. My log file sizes are the same size on each server and my backups are completing successfully. what might be causing the VLFs on the primary replica to have a status of 2 in DBCC LOGINFO when taking log backups from the secondary replica?
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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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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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Jun 9, 2014
I have 2 SQL Server replicas configured on SQL Server 2012 AlwaysOn. e.g. SQL1 & SQL2.
I have configured backup job on both SQL Server with the following statement. and the job occurs every 10 minutes.
•declare @DBNAME sysname,@sqlstr varchar(500)
set @DBNAME = 'dba'
IF (sys.fn_hadr_backup_is_preferred_replica(@DBNAME)=0)
BEGIN
--Select 'This is not the preferred replica, exiting with success';
[Code] ...
I turned off SQL2 for Windows maintenance. So there is only SQL1 is online. Afterwards. I checked the backup folder and didn't see any new backup files was created after SQL2 was offline. I rerun the job. It still doesn't backup database on the Primary Replica. Then I searched on SQL Server Book online. It says
Prefer Secondary
Specifies that backups should occur on a secondary replica except when the primary replica is the only replica online. In that case, the backup should occur on the primary replica. This is the default option.
According to what it says, it should backup on the Primary Replica.
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Aug 11, 2015
We are not able to failover the AG to secondary replica. The process gets timed out and AG goes to resolving mode. Had to reboot the box in order to switch the AG back to primary node. We even rebuilt the whole AG from scratch but the issue remains.
Failed to bring availability group 'xxxx' online. The operation timed out. Verify that the local Windows Server Failover Clustering (WSFC) node is online. Then verify that the availability group resource exists in the WSFC cluster. If the problem persists, you might need to drop the availability group and create it again. [SQLSTATE 42000] (Error 41131). The step failed.
Not much information is available in the logs.
Version : sql server 2014 sp1
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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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May 5, 2014
Assume if i have a connection(Application intent readonly) starts with reading, writing and again reading data for a report. how it will works in SQL 2014 Always availability on?
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Jun 30, 2015
I was hoping for some information regarding table triggers. We have databases that are part of an AlwaysOn availability group on SQL Server 2012. Some of the tables have table triggers defined. There are both types of triggers, INSTEAD OF and AFTER INSERT, etc.
From my understanding of how secondary read-only replicas work, I am assuming that these triggers have no impact at all when the database is a read-only secondary replica and they only fire when the database is the primary read-write database.
However, after doing a search on the internet, I have not been able to find a definitive source of information.
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Mar 8, 2015
I am trying to implement a read only replica to move much of the data read for an application to the secondary replica. Initially I had the the primary and secondary set to asynchronous commit. QA brought up an issue with creating entities from the application because after the creation of an entity the application turns around and repopulates the entire aggregate object. Well it seems that the application was reading the secondary replica before the data had been committed. Although I understand the issues that synchronous commits can cause, I went ahead and made the change as I expected it to fix the issue. After changing the primary replica to synchronous we still had the error, so I also changed the secondary although that makes no since, but the issue remains.
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Oct 14, 2014
We have a reporting database which is refreshed daily from prod backup and later creating new tables/views/indexes as part of the refresh job. Is there a better approach we can implement in sql 2012/2014 for this scenario since we are planning to migrate to sql2014.
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Jun 22, 2015
Having an annoying AG/AO problem with the read only routing side of it.
Let me give some specifics first:
2 SQL Server Instances, Not Clustered.
Availability Group is named 'Ireland'
There is a primary Replica and a Secondary Replica, named:
'IrelandPrimary' and 'IrelandSecondary'
There is a listener configured with the name 'ListenIreland' on Port 14330 (the two 3's are correct)
Read Only Routing URLS are configured as follows:
IrelandPrimary tcp://Ireland.dom.local:49891ALL
IrelandSecondary tcp://Ireland.dom.local:49841ALL
So now my problem:
When I try to connect using the ApplicationIntent=Readonly; or even using -K ReadONLY in sqlcmd I get the error telling me that my connection was actively refused.
This is connecting to the Listener, not the instance itself - that works fine. I'm at a bit of a loss now.
To explain what I am trying to achieve is a for a connection to be redirected to the secondary replica when its set for read-intent.
I've just noticed that it only fails when I specify ApplicationIntent=ReadOnly; If I omit the Intent It connects to the read-write database instead.
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Sep 15, 2015
I have 3 servers taking part in an AlwaysOn AG.
I want to grant a user READ access to only one replica, and certainly not to the principle.
How do I go about doing this?
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Oct 8, 2015
We have always on setup in our environment with read only replica. The primary database has 2 schema one is a dbo and other xyz. We have some store procs created in dbo schema and xyz schema. These store procs are being used by SSRS reports to retrieve the data (select only) no data changes will be made.
when we run the store proc from the read only server the storeprocs in the dbo schema run fine but xyz schema are failing with the message saying failed to update the database as this is a read only...
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May 27, 2015
in my secondary server the database which is in restoring state , when i checked in always on dash board "This secondary database is not joined to the availability group" ,
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Jun 9, 2015
SQL is generating dump every 1 min with error
EXCEPTION_ACCESS_VIOLATION reading address 0000000000000020 at
Server is running SP2 CU2.
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Oct 14, 2015
Environment:-
Windows 2012 R2,
SQL 2012 (Primary Replica)
SQL 2012 (Seondary Replica)
SQL 2012 (Secondary Replica over WAN site)
There are database replicating on three SQL servers. WAN line is having performance issue because of limited bandwidth I have to remove SQL secondary replica over WAN site temporarily and add it again later when the WAN line is upgraded with between bandwidth What is the best practice to remove secondary replica and replicating database and add later from SQL management studio without interruptions on databases?
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May 6, 2014
How can we change the backup replica in Always on Cluster. I am not able to take backup because of this.
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Aug 19, 2014
After failing over to the DR replica. All databases are out of sync. DR replicas were setup as async the other 2 are set up as sync. Is this by design. No data has been updated to any of these as they are test dbs. So all dbs should be the same, no data loss.
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Mar 23, 2015
I have a 2 node cluster with 2 standalone 2k14 instances having alwayson setup. As per client requirement we have created a client access point with a cname alias in dns to connect to secondary replica. Now, everytime whenerver the roles switch over one has to manually move this resource from the previous secondary node to the new secondary node. This is tedious, and should not be done manually either, so I am looking for a way to automate it so that as soon as the role switches over, the resource group after some time should also switch over to the current secondary.
Env details
xa (current primary)
y2a (secondary)
client access point (resource group): aglreadtest
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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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Sep 5, 2014
Setting up a test AlwaysOn Availability Group for one database.
However, whenever I restore the database to the replica server and join it, it ends up with my user account as the owner of the database.
Obviously I do not want a user account as the database owner, but since it is read-only I cannot modify it directly. If I were able to fail the AG over to the replica, I could change the owner then, but I cannot due to business requirements. this AG is to essentially serve as a replacement to log shipping.
I tried doing the backups and restores using EXECUTE AS login = 'sa', and yet it still shows up as my user account.
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Aug 21, 2014
In always on under availability group server name properties can see the option Readable Secondary. In that for secondary server the Readable Secondary Option is YES and for Primary it is Read-Intent. I believe Read-Intent allows only read only connections and YES allows all user connections.
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Aug 21, 2014
In always on under availability group server name properties can see the option Readable Secondary. In that for secondary server the Readable Secondary Option is YES and for Primary it is Read-Intent. I believe Read-Intent allows only read only connections and YES allows all user connections.
What exactly it means for the primary and secondary?
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Oct 3, 2014
I have a SP that runs on the primary in 18 min and 45 min on the secondary( poorly written cursor,trying to fix it).Both machines are Exactly the same.I ran them in the middle of the night when no one was on the Sec. Node as we use it for reporting.
PLE: 7,000+
AVG Disk sec/write below .01
AVG Disk sec/read below .01
CPU below 5%
both machines set a max dop 4
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Jun 27, 2015
Secondary replica database(setup in async mode) of AlwaysON went in "restricted mode" during weekly reindex operation.
So I have tried below steps
1) Executed following statement on the same secondary replica database where the issue exists
alter database <DBNAME> set multi_user with rollback immediate
but it failed with the error saying "The operation cannot be performed on database "dbname" because it is involved in a database mirroring session or an availability group. Some operations are not allowed on a database that is participating in a database mirroring session or in an availability group. ALTER DATABASE statement failed."
2) Primary database is multi_user but still tried following command on primary replia database(thinking it will replicate)
alter database <DBNAME> set multi_user
but no luck. The secondary alwaysON database shows (synchronizing) as the alwaysON is set in async mode but the command doesn't replicate across secondary
so we are left with the only option to re-setup alwaysON but I want to avoid it as database size is huge..
any other options or am I missing anything?
MCP,MCDBA(SQL 2000),MCTS(SQL 2005),MCITP(SQL 2005)
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Jul 2, 2014
I have an availability group with read only replicas, readable secondary set to yes and allow all incoming connections. I have also configured the read only routing (at least I'm pretty sure this is correct).
If I login to SSMS with a user in the sysadmin role I can view the objects in the read only replica database. If I login with a user in the public role I'm unable to get past the obvious error:
"The database databaseA is not accessbile. (ObjectExplorer)"
I've also tried adding the "ApplicationIntent=ReadOnly" option.
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Jul 20, 2015
In my environment always on is there. Today I observed that primary server fail over to secondary server .now the secondary server acting as primary role.
Can I know when is fail over is happened and who did the fail over. Is there any script to find this?
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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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