Replication :: Server 1 And Server 2 In Mirroring Relationship With Automatic Failover
Sep 24, 2015
I'm looking at a setup where they have server1 and server2 in a mirroring relationship with automatic failover.Â
Server1 is the principalThey are using transactional replication to replicate asingle databse to server3 is AWS.Distribution database is on Server1All Agents (log reader, snapshot, distributor) run on Server1Server2 has not been set up for replication...My understanding is that in this set up you would normallly place the distribution database on a separate server and enable publication on the mirror, Server2.
What happens if they failover? Replication would stop, and presumably records added while the mirror is the active database would not be marked for replication?How would they recover? Failback and reinintialize
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Mar 15, 2006
Hi there.
I´m running some tests in a database with Mirroring and without Mirroring. As expected there is a performance hit using Database mirroring.
The tests i´m running are just simple functions inserting and updating the database, and then counting the number of sucedeed inserts and updates in a time interval.
My question here is: What if i use Sql Server failover mechanism?
I know that failover time will increase and management is more complex, but what can i expect in terms of performance ?
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Jun 22, 2015
I have SQL Server 2008 R2 database mirroring setup with witness. Below database connection string is used by the application
Â
jdbc:sqlserver://<Server_A>MSSQLSERVER;databaseName=<Mirrored_DB>;port=1433;failoverPartner=<Server_B>MSSQLSERVER
Â
During some maintenance activity at the OS side , I tried to manually failover database from Server_A to Server_B. It took long time for failover to Server_B. While failing over the Mirrored_DB database goes in In Recovery status and application is not able to connect to database. I waited for long time more than 40 mins for database to come online on Server_B but it did not work.So I have recovered database on Server_B using RESTORE DATABASE Mirrored_DB WITH RECOVERY.
Â
After database was recovered on Server_B application was not able to connect to database with error as "The database <Mirrored_DB> on server Server_BMSSQLSERVER is not configured for database mirroring".
Â
My Question is
Why manual failover did not get back database on secondary server upwhy the original  connection string below is not able to connect to the database while database is online on Server_B  but without mirroring
 jdbc:sqlserver://<Server_A>MSSQLSERVER;databaseName=<Mirrored_DB>;port=1433;failoverPartner=<Server_B>MSSQLSERVER
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Apr 9, 2015
We have 2 data centers, site 1 and site 2. Â Site 1 is generally our primary, and site 2 is our Disaster Recovery (DR) site. Â I want to setup a SQL instance to have extremely high availability. Â Therefore I was looking at using DB mirroring, with synchronous data writing, high-safety and auto-failover. Â This requires the usage of a witness server.My problem with this setup, is that if the witness and principal are both at site 1, if site 1 goes away (power failure, asteroid impact, lol, anything else that would be a *true* DR scenario), then there is no failover to the mirror server at site 2. Â However, if you put the witness at site 2, anytime the WAN link between site 1 and site 2 has an issue, the DB will auto-failover to site 2. Â Is the reason for the recommendation of the witness being at the primary site because the thinking is that WAN link failure is likely more common than a *true* DR scenario that takes out all of site 1?
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Sep 29, 2015
if for any reason AG fails over to async node, how replication behaves? As data will not be in sync with previous primary replica, how replication will work? I think that we have to reset replication from scratch as there's a high chance subscribers might be more updated than current primary replica as failover to this node causes data loss. How to keep replication in sync without resetting up? Can we achieve this?
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May 25, 2008
Hi there,
I am testing the db mirroring, making sure it will auto failover. I've stopped the SQL services on my principal and then I looked at the mirror db is says it's restoring. It stayed like that for 10 min before I enabled the mirroring again. Anyone knows why it's not failing over??????
Here's my setup: SQL 2005 Standard, Server 1 Principal, Server 2 Mirror & Witness.
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Jan 25, 2007
Hi there,
We've recently set up a Principle, Mirror and Witness configuration with the Mirror and Witness in a separate building to the Principle. All three are part of the same domain (DMZ) and are different servers, the buildings are connected via a fiber optic cable. All servers and SQL Server instances are logged in with the same domain admin account DMZesAdmin.
Mirroring is all set-up and the databases are synchronized. Every once in a while some (not all, normally 6 out of 15) databases will switch roles and become active on the mirror. The SQL Server mirroring monitor job then reports:
Date 25/01/2007 12:37:01
Log Job History (Database Mirroring Monitor Job)
Step ID 1
Server DMZSQL01
Job Name Database Mirroring Monitor Job
Step Name
Duration 00:00:02
Sql Severity 16
Sql Message ID 32038
Operator Emailed
Operator Net sent
Operator Paged
Retries Attempted 0
Message
Executed as user: DMZesadmin. An internal error has occurred in the database mirroring monitor. [SQLSTATE 42000] (Error 32038). The step failed.
I have no idea, what causes the failover, it could be a slow network or a bad set-up, can anyone give me some ideas of what to do to track down the problem or any experience of what could be causing this, it happens randomly every day or three. No warning and if I go to the mirror and failover back to the principle again then it's all just fine. However I don't want half my databases working on 1 server and half on the other.
Any ideas?
Thanks
Ed
UPDATE:
I've just been looking at the logs on my Mirror and at the same time it reports in this order
Error: 1479, Severity: 16, State: 1.
The mirroring connection to "TCP://DMZSQL01.dmz.local:5022" has timed out for database "WARCMedia" after 10 seconds without a response. Check the service and network connections.
Database mirroring is inactive for database 'WARCMedia'. This is an informational message only. No user action is required.
Recovery is writing a checkpoint in database 'WARCMedia' (41). This is an informational message only. No user action is required.
The mirrored database "WARCMedia" is changing roles from "PRINCIPAL" to "MIRROR" due to Failover.
Database mirroring is inactive for database 'WARCMedia'. This is an informational message only. No user action is required.
...
This looks like a time out, is there any way to set the TimeOut threashold for Database mirroring or set retry intervals??
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Sep 28, 2007
I am developing an enterprise class solution using SQL Server 2005 and MS .NET v2 and am tying determine if SQL Server 2005 (which edition and if so how) would be adequate for my proposed solution. Any feedback, tips, comments would be greatly appreciated.
As a background the solution I am developing will be web services based and used by multiple offices around the globe by over 500 users. I have already developed a prototype using a single SQL Server 2005 instance but as this solution is going to be used by offices around the world I want to have an IIS Server and SQL Server 2005 server instance in each office with "links" back to the primary SQL Server 2005 cluster in Australia.
One of my thoughts was to set up replication between the offices that would happen at midnight remote office local time and then set up triggers to update the primary cluster when assoociated data was changed on the remote sites or on the primary cluster. Does anyone know or can anyone suggest alternatives to this strategy?
I effectively need some sort of inter site caching functionality with store and foreward capabilities ...
Thanks
Andrew
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Sep 7, 2007
Setup Configuration:
3 servers
- PRINCIPAL IP: 10.2.5.31 - DNS Lookup: db-server-2.mosside.choruscall.com
- MIRROR IP: 10.2.5.30 - DNS Lookup: sql-mirror.mosside.choruscall.com
- WITNESS ip: 10.2.5.32 - DNS Lookup: sql-witness.mosside.choruscall.com
Each Server is running Windows Server 2003 Enterprise Edition with SQL Server 2005 Enterprise Edition.
All server instances are enabled for remote connections(By default they are not).
All servers have the flag 1400 traceon and have been restarted.
PORT 5022 is unrestricted on network.
The server instances are connecting via certificates. Each server has an endpoint for the certificates to to connect on.
Certificate Setup Proceedure:
Principal_Host:
1. Create Master Key with Password
2. Create certificate with subject
3. Create endpoint for certificate (Listener_Port = 5022, Listener_ip = all)
to connect on for database_mirroring
4. Backup Certificate (principal_cert.cer)
5. Take backed up certificate to Mirror_Host
(Reapeat Steps 1-5 for Witness and Mirror)
Mirror_Host: Create Certificate on Mirror_Host for inbound connections from Principal:
6.(On Mirror_Host) Create Login for Principal using same password in step 1 (principal_login)
7. Create user for login just created. (principal_user)
8. Create local certificate for Principal on Mirror using certificate generated by principal.
ex: Create Certificate Principal_cert Authorization Principal_user FROM FILE='c:principal_cert.cer'
9. (If an endpoint has been created already on the mirror)Grant connectiion to the login:
ex: Grant connect on endpoint::mirror_endpoint to principal_login
Repeat Steaps 6-9 for Principal and Witness Servers accordingly.
10. Import Database to SQL Server 2005 Principal Instance
11. Backup Database to disk with format
12. Backup Database log file to disk with format
13. Copy backups to mirror
14. Restore Database and log file with norecovery on Mirror_Host
15. Configre Database for Database Mirroring on Principal Server
There are two ways to do this. Via the wizzard or via the Transact-SQL window.
Using the wizzard appears to work since I started using FQDN.
PROBLEM:
After configuration, everythig appears to be correct. That is, the principal displays
that it is the principal and it is synchronized with the mirror. The mirror also displays that it is the
mirror and it is synchronized with the principal and it is in recovery. If I failover manually, the mirror
becomes the principal and the principal becomes the mirror (They form a quarum). If I disconnect the principal
from the network, the mirror is supposed to form a quarum with the witness and promote itself to principal status.
This is not what is happening. The witness recognizes that the principal is down and logs that info into its log file.
The Mirror attempts to contact the witness but cannot log onto the machine. The Mirror Logs the following:
Error: 1438, Severity: 16, State: 2.
The server instance Witness rejected configure request; read its error log file for more information.
The reason 1451, and state 3, can be of use for diagnostics by Microsoft.
This is a transient error hence retrying the request is likely to succeed.
Correct the cause if any and retry.
<<<<<<<MIRROR SERVER >>>>>>>>
2007-09-06 15:08:45.32 spid23s Error: 1438, Severity: 16, State: 2.
2007-09-06 15:08:45.32 spid23s The server instance Witness rejected configure request; read its error log file for more information. The reason 1451, and state 3, can be of use for diagnostics by Microsoft. This is a transient error hence retrying the request is likely to succeed. Correct the cause if any and retry.
2007-09-06 15:09:05.32 spid23s Error: 1438, Severity: 16, State: 2.
2007-09-06 15:09:05.32 spid23s The server instance Witness rejected configure request; read its error log file for more information. The reason 1451, and state 3, can be of use for diagnostics by Microsoft. This is a transient error hence retrying the request is likely to succeed. Correct the cause if any and retry.
2007-09-06 15:09:25.33 spid23s Error: 1438, Severity: 16, State: 2.
2007-09-06 15:09:25.33 spid23s The server instance Witness rejected configure request; read its error log file for more information. The reason 1451, and state 3, can be of use for diagnostics by Microsoft. This is a transient error hence retrying the request is likely to succeed. Correct the cause if any and retry.
2007-09-06 15:09:45.34 spid23s Error: 1438, Severity: 16, State: 2.
2007-09-06 15:09:45.34 spid23s The server instance Witness rejected configure request; read its error log file for more information. The reason 1451, and state 3, can be of use for diagnostics by Microsoft. This is a transient error hence retrying the request is likely to succeed. Correct the cause if any and retry.
2007-09-06 15:10:05.35 spid23s Error: 1438, Severity: 16, State: 2.
2007-09-06 15:10:05.35 spid23s The server instance Witness rejected configure request; read its error log file for more information. The reason 1451, and state 3, can be of use for diagnostics by Microsoft. This is a transient error hence retrying the request is likely to succeed. Correct the cause if any and retry.
2007-09-06 15:10:25.36 spid23s Error: 1438, Severity: 16, State: 2.
<<<<<<< WITNESS SERVER >>>>>>>>
2007-09-06 14:19:55.90 spid52 The Database Mirroring protocol transport is now listening for connections.
2007-09-06 15:07:11.64 spid24s Error: 1479, Severity: 16, State: 1.
2007-09-06 15:07:11.64 spid24s The mirroring connection to "TCP://db-server-2:5022" has timed out for database "APS_SQL_DEV" after 10 seconds without a response. Check the service and network connections.
2007-09-06 15:07:43.20 Server Error: 1474, Severity: 16, State: 1.
2007-09-06 15:07:43.20 Server Database mirroring connection error 4 '64(The specified network name is no longer available.)' for 'TCP://db-server-2:5022'.
2007-09-06 15:08:06.03 spid9s Error: 1474, Severity: 16, State: 1.
2007-09-06 15:08:06.03 spid9s Database mirroring connection error 2 'Connection attempt failed with error: '10060(A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.)'.' for 'TCP://db-server-2:5022'.
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Nov 27, 2006
Hello,
we're running a mirrored database with High Availability for Automatic failover including a Witness instance for a web application.
When doing a manual failover on the database in Management studio, the roles are switched correctly and the database is in "Principal, Synchronized" and "Mirror, Synchronized/Restoring" mode. The web application has no problems switching servers by using client failover with the jdbc driver. There is no problem accessing the database with Management Studio.
However, if we stop the SQL service on the Principal server the role is automatically failed over to the Mirror server by the Witness. The database is then in the mode "Principal, Disconnected" which should be fine. However, accessing the database from the web application or with Management Studio yields some strange results. It is not possible to write to the database, and reading from the database works inconsistently (the web application seems like it can do it, but not from the Management Studio).
Starting the SQL service on the former Principal server makes the database go into mode "Mirror, Synchronizing/Restoring" and "Principal, Synchronizing". And it will stay that way indefinitely. There are not that many updates/transactions made to the database that can make it stay in this state, especially if you can't write to the database in the first place.
The next step taken after being stuck in this state is to stop the SQL service on the Mirror (former Principal), restart the service on the Principal (former Mirror). Accessing the database now works. The database is in mode "Principal, Disconnected". Starting the SQL service on the Mirror (former Principal) makes the database go into the normal "Principal, Synchronized" and "Mirror, Synchronized/Restoring" mode. Access to database is normal.
The same erroneous behaviour can be observed by unplugging the network cable on the Principal server, so it seems like we can only get a smooth transition by doing a manual failover.
Any ideas on what might be the problem? Has anybody experienced a similar situation?
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Jun 24, 2015
I'd like to understand why it is not possible to automatic Failover Availability Groups using Failover Cluster Instances. I think it would be great for DR and HA. Do you understand why that limitation exists?
The link [URL] ....
SQL Server Failover Cluster Instances (FCIs) do not support automatic failover by availability groups, so any availability replica that is hosted by an FCI can only be configured for manual failover.
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Nov 29, 2006
I have setup a mirror configuration with a witness to be able to use the automatic failover. The principal is DBSP01, the mirror is DBSP02 and the witness is DBSP03. I have an application running an DBCP01. When the mirroring is working, the application can connect to the database on DBSP01. I disconnect dbsp01 from the network, so that DBSP02 becomes the principal. When I try to connect the application to the database on DBSP02, the login fails. Whithout the mirroring I was able to logon to DBSP02, but as soon as it is part of the mirroring, I'm not able to connect to it anymore, whatever the state of the database is. What could be the problem? Can anybody help?
Remco
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Dec 21, 2014
I am getting alerts as Availability group not ready for automatic failover , how to check and resolve the issue ?
How to check the databases status whether they are in sync unsync in High availability ?
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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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Aug 8, 2007
In an sql authentication environment with an automatic failover in database mirroring how to you manage new logins which have been created on the principle since the start of mirroring? Since the master cannot be mirrored, and the mirror database cannot be read during mirroring (except as a snapshot) in order to find the missing logins, I assume that only after failover a script should run to create the new logins and then run sp_change_users_login . The qestions are:
1) should the script create a new login first and then run sp_change_users_login with option update_one , or should sp_change_users_login using option
Auto_Fix create the missing logins?
2) But what is the password of these users? is it initially NULL , as a consequence of sp_change_users_login? What about the SIDs?
3) Or should we bypass sp_change_users_login altogether and use
CREATE LOGIN <loginname> WITH PASSWORD = <password>, SID = <sid for same login on principal server>,...as described in http://blogs.msdn.com/chadboyd/archive/2007/01/05/login-failures-connecting-to-new-principal-after-failover-using-database-mirroring.aspx
4) What is the event that would trigger this script to run after the aitomatic failover ?
Is there a definitive MIcrosoft agreed apon and recommended method to tackle this?
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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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Dec 19, 2014
how to resolve and trouble shoot the availability group is not ready for automatic failover in sql2012
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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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Jul 12, 2007
Hello,
I am a C++/C# developer my SQL skills are very limited.
I have a database set up for mirroring and I would like to get an e-mail notification whenever an Automatic Failover occurs. Can anyone show me how to do this using SQLServer 2005? Please provide T-SQL script sample if possible!
Thanks,
-Agustin
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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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Mar 25, 2006
How can I create a one-to-one relationship in a SQL Server Management Studio Express Relationship diagram?
For example:
I have 2 tables, tbl1 and tbl2.
tbl1 has the following columns:
id {uniqueidentifier} as PK
name {nvarchar(50)}
tbl2 has the following columns:
id {uniqueidentifier} as PK
name {nvarchar(50)}
tbl1_id {uniqueidentifier} as FK linked to tbl1.id
If I drag and drop the tbl1.id column to tbl2 I end up with a one-to-many relationship. How do I create a one-to-one relationship instead?
mradlmaier
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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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Nov 8, 2006
I'm testing mirroring in a high availability mode and getting some odd results. If I kill the SQL Service (or reboot the machine) fail-over works quickly and correctly. If I unplug the Network cable though I will get some of the databases failed over and some of the databases will either be Mirroring / In recovery or Principal / In recovery and never go live. Right clicking on them and going to properties lists there error that the database is unable to communicate with the Partner or Witness. The databases that this will occur on seem to move around (i.e. it isn't always the same databases, but will often be many of the same databases). If I reboot the databases that will not fail over tend to change fairly dramatically. I've seen instances where only 3 databases would fail over (I'm testing 17 databases) and other instances where all but 3 databases would fail over. I've had exactly one test where all databases failed over correctly. Again if I reboot a principal server, fail over works every time.
Has anyone else experienced only partial failovers for network issues or have a work around?
I have temporarily created a script that will force the databases to be the principal, but it's not great for high availability (probably will work for disaster recovery though).
Thanks
Larry
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Aug 26, 2015
I have the following mirroing setup for DR.
Prinical(ServerA) and Mirror(ServerB)
When we do a DR test we do manual failover from Principal(ServerA) to Mirror(ServerB)
Now
ServerB is Prinicpal
ServerA is Mirror
Applications do their testing against the new principal which is ServerB but dont want to take those changes or sync to ServerA(Mirror).
Is there any way to do this without breaking the mirror?
Finally It will go back to original setup after the test which Server A is Principal and Server B will be its mirror.
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Feb 16, 2006
We are planning to update our two node, active/passive clustered system to SQL 2005 from SQL2K. Would we be better off to use database mirroring rather than clustering with failover? I believe mirroring takes 3 systems rather than two (one for each mirror and one for monitoring), but can the monitor be a rather low powered PC?
Our current cluster uses two 4-processor Dells and an external PowerVault RAID array with fiber channel connections. Each server has two NICs, one for general network and one for heartbeat and a fiber channel card to connect to the external PowerVault.
Here are my questions:
1 - If I understand it correctly, mirroring uses just separate servers without the need for the rather expensive and complicated shared fiber channel array that must go between them. Do I still need a shared array or can I just use internal RAID arrays in each box?
2 - Are there any advantages to keeping our current system? Our current system has worked well, but the failover takes a couple of minutes. Is mirroring faster?
3 - Is there still a virtual IP address and network name that everyone connects to?
4 - What are the drawbacks?
5 - Can I run non-mirrored DBs on the same servers or are they really locked together tightly?
6 - How much different in configuration can the two boxes be? With the cluster, I really need duplicates in every way.
7 - Do I need a separate license for the SQL Server on each box in the mirror or is one enough, since they work in lock step?
Thanks for any of your experiences on this.
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Oct 25, 2006
Hello,
I've got a question about failover with the database mirroring.
I have 3 servers, 2 with SQL 2005 and 1 with SQL Express as witness.
After getting some problems to install database mirroring with Windows authentification, i had to create an authentification by certificate.
All goes well but my problem is about my primary instance SQL alias.
The alias on the primary doesn't follow on the secondary when the primary is down.
I've searched on forums and in the internet SQL web sites, but i didn't find anything.
I create another alias on the secondary but i don't know how to modify it in T-SQL...
I would like to know if there's any solution to modify an SQL instance alias by transact-SQL? or if anyone has already install on its servers, a fail over automatic with one instance alias with data mirroring in T-SQL?
Thank you all for your help...
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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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Jun 14, 2007
Hello.
I am confuse and cant decide on how to setup high availability on our SQL 2005. Here's what on my mind and on resources list:
I plan to have mirroring on my SQL1 to SQL2 with the help of SQL3 as witness. So this would be automatic failover. My idea on mirroring is when SQL1 goes down, SQL3 would tell SQL2 to run and be the primary. It will automatically failover to SQL2. Right? My questions are:
1) How can I revert back to SQL1 once it is ready?
2) I read in one of the post that it is impossible to write in a mirrored DB, is this true? I mean, what's the use of failing over to the next node when it's not possible to write and update data/records?
3) If number 2 is false (i hope so), how would the data be synchronize from SQL2 back to SQL1. Those transaction that were made while SQL1 is down.
4) How about the connection string from the web applications? Would it be automatically point to SQL2? We have load balancing setup in place, would this help web application connection to automatically point to SQL2?
Another setup:
We have SAN in place (not yet used, but is planning to use for this SQL thing), EMC to be specific. My question would be:
1) For SAN setup, the data storage would be centralize. So would that mean that SQL1 and SQL2 services will use the same data and log file from the SAN storage?
2) How would you call this setup then? Can this be clustering type of high availability? Will clustering work under load balancing setup? I believe mirroring is not possible here? Right?
3) How can I setup my 3 SQL servers with the same theory in mind: when SQL1 goes down, SQL2 will take over. Data will be synchronize when SQL1 is up and running again. With automatic failover and reverting back to primary.
I read so much topics about this, but the more I research, the more I get confuse.
Any suggestions, comments, advice is greatly appreciated!
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Oct 16, 2007
Hello everybody,
I'am currently testing a MSSQL 2005 mirroring implementation with automatically failover.
1 principal server ====> Server A
1 mirror server ====> Server B
1 witness server ====> Server C
When server A fails Server B becomes Principal. ( which is the general idea ) This is working perfectly.
The problem is when i try to connect to the mirror Server B ( actually the new principal )
I use the .NET connection string with the failover parameter ( even without the parameter ) the connection fails.
( the general error : unable to connect, or connection property has not been initialized )
Data Source=ServerA; Failover Partner=ServerB;Initial Catalog=DBMTest;uid=dbuser;pwd=dbpassword;
This connection property works fine when server A (original principal) is online.
When i run the SQL profiler with the mirror db as profile, i dont see the traffic.
So you think the mirror server has a network problem or was not connfigured for remote access.
i thought that also, but when i create a 'stand alone - non mirrored' database the same application with the same connetion string ( well.....different db) works fine.
The problem must be in the whole mirroring implementation....... ( my idea )
Does anyone had the same problem, or better, doed anyone know how to solve it?
Hope to hear from you soon!
Thank you in advance!
Regards,
W.schmitt
The netherlands
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May 3, 2008
Server A = primary SQL DBs (mirroring origination)
Server B = failover SQL DBs (mirroring destination)
For database mirroring a witness is required.
Can the witness live in another instance of SQL on server B?
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Aug 30, 2006
hi there
I am using SQL SERVER 2005.
I am creating a Merge replication(between two databses), its working well, but i need to goto the Local publications & right click there & select the "View Synchronization Status" & then start the Agent manually to Synchronous the databases.
Now I want the Two databses should be replication (Merge) automatically without going to any menu.
I mean the Synchronization takes place when any of the Databases changes, automatically, without touching anything.
For Example:
If one record is inserted in a table(on commit) of Database ONE, it should be Reflected to the other table of the database TWO.
Any Idea, or Link or solution???
Gurpreet S. Gill
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Feb 21, 2007
Under EM's Replication Monitor/Publishers/pub1/publisher1 there is a "Validate Subscriptions" option on the right-click menu. Since I see unexplained Replication Validation activity I think that the "Validate Subscriptions" option is turned on. But there is no "turn-off" button or way to say "stop." Does anyone know how this "feature" works?
Thanks
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Jun 5, 2008
Dear All,
we have one production server and continuously getting the data from application.
we have replication server with transactional replication for the main database.
so, for taking the data, we are using prod server, and for fetching the data, we are using replication server.
now what i'm expecting from you is, if something happend to the main server, there is no cluster except backup. what is the best plan for this?
and one more thing, if replication server fails, then the application will not fetch the data then what is the plan for this?
please give me a good plan for this kind of strategy.
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