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SQL Data Compression vs SAN compression

June 24, 2019, 5:02 am
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Iam currently investigating what the impact in terms of reliability, data savings and performance when using SQL Data Compression on top of SAN compression.

I have done some investigation, but there are not a lot of articles regarding this. At least, they do not anwser the questions that I have. I have found a Dell whitepaper which states to use either one of the options. We do not have a Dell SAN, but that would possibly make this also applicable for our storage unit (Huawei).

Reliability: I have 'heared' stories where data could become corrupt when you use both. I cannot find anything that talks about this, but could be plausible. We could however take this risk with our relatively small datawarehouse. We have ETL timing issues there and if corrupt, it is easy to reload the data from the source.

Data savings: The hardware would probably be better at this. Since SQL also only compresses IN_ROW_DATA, you can always get a higher compression ratio out of the SAN compression.

Performance: Since data is compressed, SQL needs to perform less I/O requests, so in terms of performance we could win a lot here. I don't think that this has anything to do with the compression on storage level, because there are simply just less I/O requests going to the storage unit. The storage unit always needs to return data for every I/O request regardless if it is compressed. If data is compressed and 4 I/O requests are done for the same block, then the storage unit still needs to return 4 blocks of data. So if we can reduce that, then that is a win. Also, SQL writes compressed pages to memory, so we could win performance here as well.

What would be the recommendation regarding the 3 statements above? I cannot find really any good articles regarding this. Maybe some of you know a few?

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Restore database in Always On Availability Group failed for 1 of 3 nodes.

June 24, 2019, 9:09 am
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Database had been improperly configured as standalone (no in AG group) on Node C.

To fix the issue I did the following: I backed up database and detached from Node C.

Node C is now and was also at the time a secondary in the AG group.

Went to primary Node A restored database onto Node A, added database to AG group, initially got error regarding Node C..I had to delete file database.mdf from Node C and then AG wizard succeeded. Now the restored database has synchronized to Node A and B, but it's failing on C. Error on restored database in AG dashboard of Node C states the following:

Data synchronization state of availability database is not healthy.

What is the proper procedure to handle this issue? Help? Please and thank you.

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Transnational Replication

June 25, 2019, 8:01 am
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Hello All ,

Can we create 2014 enterprise as a publisher and 2012 standard as a subscriber for transnational replication ?

Br

ChetanV

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Why I cannot have Availability Group on my SQL Server 2016?

June 25, 2019, 8:02 am
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SQL AG script adding DB's Automatically

June 25, 2019, 9:43 am
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Hi All:

We are in the process of creating our own scripts, when ever the application creates new database, the DB will be add to Alwayson group and its working fine for us.

Today, we are planning to add one more check.

For some-reason, if the secondary replica having same database - we want to delete it.

Is it possible to delete it from Link server?

Link server already created with @notename in below script.

When we try to delete manually also, not working using link server.

Drop database [linkservername]..[test1234]

=====================================
Error:
Msg 102, Level 15, State 1, Line 43
Incorrect syntax near '.'
==================================

This is what we are trying to with hard luck, any suggestions.

     declare @avagroupname  nvarchar(128)='',
             @tsql_restore  nvarchar(1000)='',
             @tsql_hadr     nvarchar(255)='',
             @debug int,
             @dbname nvarchar(255)='';
begin

set @dbname = 'test1234';
set  @debug = 1;
set @avagroupname='AG2016'

-- if there is a same database on the secondary node , will be deleted first
        -- get the note list
       declare @notename nvarchar(128)
       select  top 1 @notename= dh.replica_server_name from  sys.availability_replicas dh join sys.dm_hadr_availability_replica_states dap
       on dh.group_id= dap.group_id and dh.replica_id=dap.replica_id join sys.availability_groups ag
       on ag.group_id=dap.group_id where role=2 and ag.name =@avagroupname  order by dh.replica_server_name desc
       print @notename
       --end
        --while @@ROWCOUNT>0 --and @notename  is not null
          --  begin
            print 'test';
                 set @tsql_restore=N'
                     exec (''if exists (select * from sys.databases where name='''''+@notename+'..'+@dbname+N''''')
                     drop database '+@notename+'..'+@dbname+N'';
                    
                    
                 if @debug>0  print @tsql_restore
                   exec (@tsql_restore)
                    
                     ---
                      
                    
                 select  top 1 @notename= dh.replica_server_name from  sys.availability_replicas dh join sys.dm_hadr_availability_replica_states dap
                  on dh.group_id= dap.group_id and dh.replica_id=dap.replica_id join sys.availability_groups ag
                  on ag.group_id=dap.group_id where role=2 and ag.name =@avagroupname and dh.replica_server_name<@notename   order by dh.replica_server_name desc
            --end

end
=================

Thanks,
Satish Kumar

Thanks, Satish Kumar. Please mark as this post as answered if my anser helps you to resolves your issue :)

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Operating system error 665

June 25, 2019, 10:40 am
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We are getting below error in one of SQL Server 2016 (Microsoft SQL Server 2016 (SP2-CU5) (KB4475776) - 13.0.5264.1 (X64))

DESCRIPTION:   F:\MSSQLSERVER\MP1\Salesorders01.ndf_MSSQL_DBCC9: Operating system error 665(The requested operation could not be completed due to a file system limitation) encountered.

I have already worked with our windows and storage guy about disk fragmentation. They confirmed that there is no issue at storage level.

Please provide some idea that how to proceed?

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SQL AlwaysON - How long data movement can be suspended?

June 25, 2019, 11:14 pm
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Hi Guys,

I have setup a alwaysON between on prem and azure server (Iaas). The setup is working fine and able to perform failover/failback. The requirement is,since these are test machines , I dont want to keep the Azure server online all the time. To reduce cost , want to keep it in stopped state and bring up whenever I perform next DR activity. 

The question is, can I keep the data movement in suspended state for such long time ( more than 3-4 months) . 

whats the best practice to handle this? ( Remove all dbs from AG group and add it back whenever necessary?). 

Please help. 

Regards

Thahif

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Failed to join replica server to Availability Group

June 26, 2019, 6:59 am
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-I have two SQL Server 2017 Developer VM on Windows Server 2016 in Azure. (SQLServer1VM and SQL Server2VM)

-Servers are not in same domain or network.

-I have enabled Always On High Availability from SQL Server Configuration Manager in both servers.

-I have SQL Server Management Studio in SQLServer1VM and I can access SQL Server2VM database with SQL login.

-I try to create Availability Group in SQLServer1VM. It find replica server SQL Server2VM

 

But I get following error. What could be issue?


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Extend On-Prem AlwaysOn to Azure - Questions

February 15, 2019, 8:16 am
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Hello,

I want to extend on-prem AlwaysOn AG to Azure.  We currently already have AlwaysOn AG setup and running.  We want to create additional replica(s) in Azure for HA.  Here's my question: in addition to creating the Azure replica(s), do we need to create an Azure Domain Controller for this setup?  Is this an absolute requirement?  I have not been able to definitively find the answer.

Thank you

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how to change HostRecordTTL value for network name 'Name: "my cluster name'

June 11, 2019, 6:22 am
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Warning "the HostRecordTTL property for network name 'Name: "cluster nmae' is set to 1200 (20 minutes). For multi-site clusters the suggested value is 300 (5 minutes)." shows in the cluster vaslidation report. how to change this cluster parameter?

the "cluster name", for exmple, cluster1 , is not listed in the outputs from get-clusterresource. off course, the paramenter of cluster cannot found from get-clusterparameter

My cluster is consist of two nodes in Server 2012 R2.

three SQL alwayson groups icreated n SQL 2016 standard on each node. These groups are Roles of the cluster and they are lsited in the ourput from get-clusterresource. But no cluster name in the ouput.

how to change HostRecordTTL value for network name 'Name: "cluster name'?

Please advise.

thansk

John

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Option_spec syntax not mentioned in create external language document

June 27, 2019, 11:15 pm
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SQL Server 2016 Always On Endpoint creation fails

June 28, 2019, 5:53 am
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Hi Experts,

I have a standard setup of two Nodes (SQL1 and SQL2) and want to create two Always On avaibality groups for two instances, each hosting a single user database.

I have created the first Always On availability group without any issues. I used port 1433 TCP for the listener and used5022 as an endpoint. Both SQL1 and SQL2are added and the SQL1 has the Primary replica.

Now I wanted to do the same with the other Database, but this time use SQL2 a Primary. In the "New Availability Group Wizard" I am configuring different endpoints for the 2nd AG of course and I am taking 5023 as port. I am also usiong a unique Listener name and IP of course. The problem is that when I try to complete the wizard I get following error:

The Database Mirroring endpoint cannot listen on port 5022 because it is in use by another process. (.Net SqlClient Data Provider)

This is very strange as in both in the cofiguration and also on the Summary page I see that the endpoints should be on5023. 

Any ideas on what I am doing wrong? Do I need to create an endpoint on 5023 in advance? I though the Always On AG wizard will do that for me?

Regards,

 

(Please take a moment to "Vote as Helpful" and/or "Mark as Answer" where applicable. This helps the community, keeps the forums tidy, and recognizes useful contributions. Thanks!)Blog: https://blog.pohn.ch/ Twitter: @StoyanChalakov





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read only replica and cross-region standby database for SQL Server 2014 EE

June 28, 2019, 8:31 pm
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Hi, Gurus, 

I am new to SQL Server and looking for suggestions. 

We have a MSSQL database running SQL Server 2014 EE. Planning to create a read only replica within same data center and a standby database  in remote region. 

Have been searching options from google and found this forum. 

For read only replica, we just want to offload the read operations to a different server . In this case,  which option is  better ,  transaction replication or always on availability groups? 

For standby in remote DC, its is mainly for HA/DR purpose. Will mirroring be a good choice? 

Thank you 


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Two failover clusters on one windows cluster

June 30, 2019, 11:54 pm
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Can I create more than one SQL server failover cluster on the same Windows cluster.

One for CRM database and the other for SharePoint databases.

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Cluster role fails to come online

July 1, 2019, 2:20 pm
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One of the instances in our Always-On cluster fails to come online. The instance is located in our DR cluster.

The following is found in the cluster events: "The Cluster service failed to bring clustered role 'SQL Server (NICD_DR_TFS01)' completely online or offline. One or more resources may be in a failed state. This may impact the availability of the clustered role."

From what we have found it seems that the storage for the instance is located at drive letter S: but the instance is looking for it at drive letter U:

This is what we found in the event viewer on the host server:

FileMgr::StartLogFiles: Operating system error 2(The system cannot find the file specified.) occurred while creating or opening file 'U:\MSSQL11.NICD_DR_TFS01\MSSQL\DATA\modellog.ldf'. Diagnose and correct the operating system error, and retry the operation.
FCB:<g class="gr_ gr_458 gr-alert gr_gramm gr_inline_cards gr_disable_anim_appear Style replaceWithoutSep" data-gr-id="458" id="458">:Open</g> failed: Could not open file U:\MSSQL11.NICD_DR_TFS01\MSSQL\DATA\MSDBData.mdf for file number 1.  OS error: 3(The system cannot find the path specified.).

The cluster manager shows that the drive should be S. This was also confirmed as correct in Explorer and storage for a different instance exists at drive letter U: (this instance using drive letter U has zero issues).

How can we correct this?


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not synchronized

July 1, 2019, 4:22 pm
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Our regualr DBA is out sick and one of our DBs in SQL2016 AG is showing that the two secondaries are out of synch.  I can confirm connectivity by pinging on the AG listener and i think it was a network issue at first that has been resolved.  I can't get them to synch back up.  I tried suspending data and resume but ti still fails.  What is my best approach to fix this? 
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"Select backup devices" hangs after clicking Add button

October 18, 2015, 4:44 am
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I'm trying to restore a database using SSMS GUI. In "Select backup devices" window if I click the Add button there the window and the whole process hangs like it will never work.

I tried to clear backup history, but that didn't solve it.

I tried with a couple of other databases, but same thing.

It was working fine!

Any advice please!

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Random Cluster Failure

July 2, 2019, 10:51 pm
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Hi There,

I have a 3 node AlwaysOn Availability Group cluster. Each node a has vote for quoum and there is no witness.

Node 1 and 2 are in the same data center while node 3 is in a remote data center connected by a high speed layer 2 link. All nodes are on the same subset. Node 1 is a primary for one AG1 and node 2 is a primary for AG2 while node 3 is only a secondary for both AGs.

The other night node 3 crashed (the hypervisor went down) which seems to have caused nodes 1 and 2 both to fail at exactly the same time a few minutes later, which seems odd as the whole point of the cluster is to avoid this scenario.

In the system event log I can see the below error on nodes 1 and 2 which I believe is the result a failed health check.

Looking in the failoverclustering diagnostic log on nodes 1 and 2  I see the this error just a second later and then the cluster service is terminated on both. I've searched the internet for references to "GumLockIsStuck" but come back with nothing but I believe this is related to updating the cluster databases with the cluster status on all nodes.


Because the above error was referring to no reporting for 600 seconds I went back 10 minutes in the same log and could a whole bunch of errors like this one stating nodes 1 and 2 were unable receive an ACK from node 3 which had of course crashed (around this time).

So what looks like has happened is node 3 has gone down and nodes 1 and 2 can't update the status of the cluster and because of that they have then stopped the cluster service on themselves. This doesn't seem right at all so can anyone explain this behavior?

Cheers
C

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Cloud Witness and Access Keys

July 2, 2019, 6:55 am
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In our company we have a 2 node Cluster using AGs across them in an IaaS setup in Azure.  For quorum we are also using a cloud witness.

Security have come to me saying they want rotate the Primary Access Key on the storage account.  I understand that this means I will have to update thecloud witness using the Secondary Key Access.  Is this as simple to do as running through the configure cluster quorum wizard and on the configure cloud witness screen using the Secondary Key?

Also what would I do if they also want to rotate the Secondary Access Key as well?

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Snapshots interfering with differential backups

February 19, 2013, 2:23 pm
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1- Setup full backs to happen Saturday nights.

2- Setup differential backups to happen every night, execpt Saturdays

3- This is on a VM machine, and we take a snapshot of it every Wednesday night.

4- SQL Server records the snapshot as a valid, full backup, although it is marked as is_snapshot = 1.

5- All differential backups after the snapshot are rendered useless. They are done based on the snapshot backup, not on the actual valid full backup done on Saturday.

After research I found KB article 951288 (http://support.microsoft.com/kb/951288). Apparently this is a Microsoft issue.

So, how do we tell SQL server to ignore the snapshot backup when doing the differential backups? And no, we do not want to stop doing our snapshots on Wednesdays. Is there a solution or a work around to this?

This is really annoying and dangerous that SQL Server would consider these snapshots as valid, viable full backups on which to base its differential backups.

Help much appreciated,

Raphael

rferreira

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