I'm looking at replicating our primary SQL server to a secondary offsite server (linked via 100Mb so effectively LAN speed). What are people's preference when deciding on a solution?
On the surface mirroring looks much better but having dug a little I've found it is recommended only 10 databases are mirrored per instance. That said, I've found a post from someone who is upto 58 databases mirrored. Are there similar limitations with log shipping?
Does anyone have any experience of mirroring and is using it in prefence to log shipping?
Our current recovery strategy is the classic restore the SQL dump from tape onto a rebuilt server so either method will be a vast improvement. None of our databases are mission critical that they need upto the second replication. 15 minute replication would be fine leading me to think that log shipping may be better given the possible limitations of mirroring
For recovery, I was considering amending the DNS records of the Database servers. Does anyone see any issues with this approach? I understand there is a automatic failure function if using mirror but this may require the application to be coded correctly?
I'm interested in how Combining Log Shipping and Database Mirroring works when failover occurs. From SQL BOL, it says:
"Topic: Database Mirroring and Log Shipping ... To run in high-safety mode with automatic failover the mirroring session is configured with an additional server instance known as the witness. If the principal database is lost for any reason after the database is synchronized and if the mirror server and witness can still communicate with each other, automatic failover occurs. An automatic failover causes mirror server to assume the principal role and bring its database online as the principal database. For more information, see Automatic Failover [ http://msdn2.microsoft.com/en-us/library/ms189590.aspx ] . If the log shipping backup location is accessible to the new principal/primary server, its backup jobs begin to ship log backups to that location. The database mirroring synchronous mode guarantees that the log chain is unaffected by a mirroring failover and that only valid log is restored. The secondary servers continue to copy log backups without knowing that a different server instance has become the primary server. ..." Source: http://msdn2.microsoft.com/en-us/library/ms187016(d=printer).aspx
Could anyone tell me that how the database mirroring synchronous mode guarantees that the log chain is unaffected by a mirroring failover and that only valid log is restored?
Let me elaborate the situation (if anything I said is incorrect, please correct me ) Here is the time line of the failover happens:
------- tn-1 ---------- tn ---------- tf -------- tn+1 ---------------> t
----------------> t: the time line. tn: the moment that the log shipping backup job and copy job is done for the transaction log obtained between the time interval tn-1 and tn. tf: the moment that mirroring failover occurs in the database mirroring session. the time interval between each tn and tn-1 are constant, say h seconds, for all n are positive integers.
Here is the question that I want to ask: In database mirroring synchronous mode, it guarantees that all the committed transaction from the moment tn to tf is copied to the mirror database. All the transaction log backup for log shipping are done on the original principal before the moment tf. After the mirroring failover occurs at the moment tf, how the log shipping mechanism guarantees that the transaction log between the interval tn and tn+1 that can be unaffected by a mirroring failover? That's the point that I interested in.
Up to now we have gotten by without having any local DR copies of servers (if a sql server goes down we are usually able to get it back in less than 3 hours). But I want more now. I want to trim the "down" window to no more than 5 or 10 minutes. (Immedate failover would be nice but is not an essential requirement. The essential requirement is to loose no data!)
I have a spec of knowledge in these areas:
SQL 2005 Clustering (requires approved hardware, quorum disk, etc. involved)
SQL 2005 Replicaiton
SQL 2005 Log Shipping.
SQL 2005 Database mirroring. ( needs three servers)
Which approach do you think is the most straightforward, sparing of hardware, yet reliable way to get us back up and running after a sql server failure.
Can anybody tell me the differences, advantages and disadvantages between these three solutions? When do I may use one or another? Could you recommend me any documentation?
We are planning to upgrade the SQL Server in our production environment from SQL Server 2000 to SQL Server 2005. This is a 4 Node cluster environment with 3 Databases on 3 Virtual instances. The main requirement is to achieve this with no/minimal downtime.
Could you please suggest or direct me to any documentation for the best practices used to upgrade such an environment?
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!
I've read a lot of the information about this topic in MSDN. My boss askme to understand and to let working an example application of Cluster Mirroring. The problem is that i dont understand well yet what is a Cluster and what is the main idea behind it.
If someone really understand and can explain me clearly whats behind it, i will be very grateful. Thanks a lot for the help. ( Sorry for me english :( )
I am trying to create a failover cluster without the log shipping in 2012 as i've done it with a static instance with some database.Is the "AlwaysON" feature the solution when an application creates random and numerous databases within the instance and we need a failover scenario ?
I have configured active passive cluster in production environment. And we also have a dr which we have configured with asynchronous mirroring with no witness. Currently active node(node
a) is in sync with dr. When failover happens and the second node(node b) becomes active, the mirror is broken and goes to disconnected mode.
But when we failback again to node a mirror is connected again and is in sync again. In our setup we have active passive cluster and a standalone server as dr.
I was hoping to learn from real world experience regarding the hardware requirements for SQL 2005. For both the 32 and 64 bit OS the minimumn recommendaiton is single processor, 1GB or more, 512 MB RAM.
This seems very thin and I was wondering if anyone had recommendations for hardware configs for a mirrored db cluster? I'm filling in as a DBA and apologize for the ignorance.
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.
I have setup database mirroring for one big database.But now Transaction log is full and server is down. What should i do? We do bulk-insert in that database.
I have a 20 GB SS2005 database that I would like to be replicated to a dev server for testing purposes. I might have some issues with the firewall blocking ports. I haven't read up on the specifics of how log shipping works yet, but I assume that is the best approach. A daily transfer would suffice.
A few options I am considering:
1. use the built in stuff, but I'm not sure it will work with our security settings, and if the trans logs are large it might be strained.
2. writing a small custom app to zip up the log file then ftp them down to the dev server. This could run nightly.
3. some third party util, such as FolderShare could transfer the log files
Using SQL Server 2008, we would like propose mirroring between two servers of a critical database. Since we initiate, may require to clarify on its purpose and also required changes from application end.Any changes required from OS Level? (I believe both servers IP or Host name should be added in host entries. Mirroring ports should be allowed/open including Principal and mirror server IP Addresses): Windows Team.Any changes required from Application? (Instance name, authentication: user name and its password should be added in web config files): Application Team.Any changes required from Network Team?Also for mirroring both the principal and mirror servers should be with same version, does it only mean SQL Server 2008 versions are enough or does it also mean to say build numbers 10.00.4000 should also be same.URL....
We have log shipping for databases from production to back office (BO) environments for users to run reports. In preparation for moving a back office environment to a different server, we want to setup an addition log shipping environment, let’s call it BO2, same as the BO. One of the challenges we had was the amount of time it would take to get the full backup from production to BO2 due to the size of the database. It would take days just to transfer the full backup.
Solution:Let’s just say the database being logged shipped is DB123. Instead of using the full backup of DB123 from production, we use the mdf and ldf of DB123 from current log shipped database on the BO to setup the additional log shipping on BO2.
Steps:1.Setup the directory structure for the undo file (tuf) on the BO2 server same as the BO server.
Note: The undo can be moved to different drive after the log shipping is setup.
2.Stop SQL services on the BO server.
3.Copy the undo file (tuf), mdf, and ldf files of the log shipped database, DB123, from server BO to server BO2.
Note: Keep these files as main copies because they will be used multiple times. Do NOT copy files to where you’ll put the new database files.
4.After the files are copied, start SQL services on BO.
5.On the BO2 server, create an empty database DB123 with database name, file_id, logical names, physical names exactly the same as the ones on the BO server. Note: Make the size of mdf and ldf small so it doesn’t take long to create the database.
6.Stop SQL Services on the BO2 server.
7.Overwrite the new mdf and ldf files of the empty database DB123 with the mdf and ldf files that were copied over from BO.
8.Start SQL services on BO2.
Note: If the file_id, logical names and physical names are not matching up, the database will be in suspect mode.
9.Do a backup of DB123 with COPY_ONLY.
10.Drop DB123 on BO2 after backup is complete.
11.Use the full backup from previous step to setup log shipping of DB123 on BO2.
Note: Below was the LiteSpeed syntax that was used
13.Again, overwrite the mdf, ldf and undo file (tuf) of DB123 on server BO2 with mdf, ldf, and undo file (tuf) from BO.
14.Start SQL services on BO2.
15.Replay transaction log from PRD
Note: You can change the location of the undo file by copy the current undo file to the new location and point to new location in “STANDBY” parameter. DO NOT do cut and paste of undo file but do copy and paste.
It works on Microsoft SQL Server 2008 R2 (SP2) - 10.50.4033.0 (X64) . I have not tried it on SQL Server 2012 yet.
In steps that stop/start SQL services, you can bring the database offline/online.
In a way, this is doing detach/attach a log shipped database.
Hello, My question is simply: according to BOL, a DB snapshot taken from a Mirror is read-only. Say I wanted a temporary (disposable) read-write DB created from the snapshot. Is there a way to generate a writable temp DB (that's not tempdb) from the snapshot? Thanks,AK
Im running some tests in a database with Mirroring and without Mirroring. As expected there is a performance hit using Database mirroring.
The tests im 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 ?
I get a general question about the feacture "Database Mirroring". Is it support by SQL Server Standard. Edition without SP1?? Of i still need to upgrade the server from SQL Server 2005 to SQL Server 2005 with SP1?
Another question: are there any problem if the one machine(server) has installed SQL server 2005 Standard edition and the other with "Developer Editon".
I hope some one can answer my question. Thanks anyway!
I have setup database mirroring with witness server. To prevent unnecessary failover because of network slow or other issue, I changed the timeout setting as
ALTER DATABASE <Database Name> SET PARTNER TIMEOUT 120
Which I understand if connection is broken between principal and mirror, principal database will wait for 120 second and after that only automatic failover will happen.
If this is true, it does not happen in my case. Failover happens before120 second.
I have multiple SQL 2008 severs with databases. Also, 1 mirroring server in place.
Since my database count is increasing can i have only 1 mirroring server. Is there any limit of db at mirroring server. I would have approx. 150 databases.
I have created mirroring... one of the column is encrypted on mirror database and I can see the decrypted result when I do query when I actually logged into server (through remote connection) but when I use the same query through using SSMS from my laptop the query result come as the column is not decrypted,
I am trying to enable database mirroring for 100 database. It goes error free till 59 databases (some times 60 databases) with the status (principal, synchronized) on principal. on the 60th or 61st database it gave the status (principal, disconnected). Also mirror starts acting abnormal. connection to mirror starts to give connection timeout and it is not enabling database mirroring on any more databases. I have SQL SERVER 2005 Enterprise with SP1 on the servers. witness is not included yet.
this are my test servers... i have more than 500 databases on my production servers.
principal and mirror both are using port 5022 for ENDPOINT communication.
I have a download "SQL Server 2005 Evalution Copy". I installed it to 3 machine, 1 - XP Professional (Witness) and 2 - Windows Server 2000 (Principle and Mirror) . And I want to try Database mirroring.
However, after restore the Log into mirror server I try to execute the following statement in Principle Server:
ALTER DATABASE TestDB SET PARTNER=N'TCP://[10.0.200.2]:5022' GO
The above 10.0.200.2 is the mirror server IP address.
it show error message as:
Msg 1416, Level 16, State 31, Line 1 Database "SCMPGroup" is not configured for database mirroring.
In Miorror Server
I execute the statement :
ALTER DATABASE TestDB SET PARTNER=N'TCP://[10.0.200.1]:5022' The above 10.0.200.1 is the principle server IP address.
It shows sucess
ALTER DATABASE TestDB SET WITNESS=N'TCP://[10.0.15.146]:5022'
it show error message as:
Msg 1416, Level 16, State 1, Line 1 Database "SCMPGroup" is not configured for database mirroring.
Please help me! I down't know if NT4 domain or evalution copy problem in there.
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.
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".
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
I am trying to enable database mirroring for 100 database. It goes error free till 59 databases (some times 60 databases) with the status (principal, synchronized) on principal. on the 60th or 61st database it gave the status (principal, disconnected). Also mirror starts acting abnormal. connection to mirror starts to give connection timeout and it is not enabling database mirroring on any more databases. I have SQL SERVER 2005 Enterprise with SP1 on the servers. witness is not included yet.
these are my test servers... i have more than 500 databases on my production servers.
principal and mirror both are using port 5022 for ENDPOINT communication.
All of the databases are critical and all must be included in the Database Mirroring. so, after that I tried to implement database mirroring again...... System has 3 GB of RAM, SQL SERVER (Mirror) using 85 MB of RAM but still giving this error while trying to enable database mirroring for 37th Database.....
"There is insufficient system Memory to run this query"
I have setup a database mirroring session without witness - ServerA is the principal, ServerB is the mirror,. Each SQL Server instance is hosted on its own machine on sql2005 EE SP2. The mirroring is working correctly. If I submit to server ServerA command:
ALTER DATABASE MYDBNAME SET PARTNER FAILOVER
, ServerB becomes the principal, it means that mirroring works correctly.
My issue is with the SQL Native Client and a front-end ASP application (actually IIS 6.0 site) that needs to make use of this database. I have setup my front-end application to use SQL Native Client and specified the failover server in connection string. Here is the connection string that I am using :
Everything works perfectly on my front-end application when ServerA is the principal. If I execute on server ServerA command:
ALTER DATABASE MYDBNAME SET PARTNER FAILOVER
, ServerB 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 ServerB. The error appears:
Microsoft SQL Native Client error '80004005'
Cannot open database "MYDBNAME" requested by the login. The login failed.
This behavior my appication till I unload IIS 6.0 pool application. After that my front-end application becomes work correctly with ServerB.
When I swap server, I execute on server ServerB command:
ALTER DATABASE MYDBNAME SET PARTNER FAILOVER,
my IIS 6.0 application automaticly turn back to ServerA without any action on my side.
I am using SQL Native Client last version http://download.microsoft.com/download/2/7/c/27c60d49-6dbe-423e-9a9e-1c873f269484/sqlncli.msi (issued in February 2007). Has anyone experienced this issue? I'm thinking that it's a problem in the SQL Native client
