Questions tagged [clustering]

A cluster consists of a group of computers connected so that in many respects they can be viewed as a single system.

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Does restart in FCI/AG mean node restart or sql server cluster aware services restart?

There are failure condition levels for FCI and AG. I read the keyword restart. Just want to confirm whether restart means node restart or sql server cluster aware services restart?
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Unlike FCI, doesn't AG make use of heartbeat to check for server down?

SQL AG in WSFC checks whether server is down via the lease timeout Where as SQL FCI checks whether server down via heartbeat Does the SQL AG not make use of heartbeat at all? Below is a sample log ...
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Is disk witness still the recommended best option for 2 node cluster (versus file share) in SQL server 2019?

Link: https://docs.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-r2-and-2008/cc770830(v=ws.10)#local-two-node-cluster It says that the disk witness is the recommended best ...
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Does dynamic quorum having any solution for partition in time?

Assume 2 node 1 file share cluster (Node 1 is active), where say the file share is down for some reason. The dynamic quorum will allow cluster to continue working and assign the voting capability ...
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In WSFC, can the child volume be shared among instances? and if so, then what is the purpose of this (sharing)?

Link: https://docs.microsoft.com/en-us/sql/sql-server/failover-clusters/install/before-installing-failover-clustering?view=sql-server-ver15#Hardware The base drive, the one with the drive letter, ...
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During scheduled maintenance of secondary node, should I set the non-primary node weights to 0 or should I set the FailoverConditionLevel to 0?

During scheduled maintenance of the secondary nodes in an FCI, should I set the non-primary node weights to 0 or should I set the FailoverConditionLevel to 0 to prevent the failover/restart?
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When the connection is lost, then does the Resource DLL restart the timeout ignoring the previous calls?

The following items describe how this property affects timeout and repeat interval settings: The resource DLL calls the sp_server_diagnostics stored procedure and sets the repeat interval to one-third ...
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Where does the WFSC resource group reside?

https://docs.microsoft.com/en-us/sql/sql-server/failover-clusters/windows/failover-policy-for-failover-cluster-instances?view=sql-server-ver15 The active SQL Server instance periodically reports a ...
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What are the specific changes that need to be made in client code to handle multi-subnet FCI?

The client application then retrieves all registered IP addresses from the DNS server and attempts to connect to the addresses either in order or in parallel. This means that client recovery time in ...
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Why does WSFC recommendation include configuring odd number of votes when this is automatically handled by dynamic quorum and dynamic witness?

Link: https://docs.microsoft.com/en-us/sql/sql-server/failover-clusters/windows/wsfc-quorum-modes-and-voting-configuration-sql-server?view=sql-server-ver15#RecommendedAdjustmentstoQuorumVoting Odd ...
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How to prevent split brain scenario in multi subnet cluster during network failure between the subnets?

Suppose I configure a multi subnet cluster say with 3 nodes in subnet1 and 3 nodes in subnet2. Since the total count is 3+3=6, which is an even number, one of the nodes will be auto assigned 0 weight (...
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What is the voting process in WSFC?

Node and File Share Majority. Similar to Node Majority quorum mode, except that a remote file share is also configured as a voting witness, and connectivity from any node to that share is also counted ...
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What is the concept of service master key in FCI?

In a single sql server instances, sensitive data like passwords in linked server and credentials are encrypted using the server master key. The key or objects can be decrypted only by the sql service ...
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How does FCI guarantee data consistency and integrity?

FCI technology uses windows clustering to start-up the sql server service on the secondary node and provides the secondary node with the data and log disks. Assuming the OS on node 1 crashed, and the ...
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How to check whether or not dynamic quorum and dynamic witness is enabled on WSFC?

Dynamic quorum and dynamic witness are abilities of the WSFC to dynamically adjust the vote of the nodes and witness to prevent unnecessary failovers. Where can I check whether the WSFC configuration ...
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How to manage patching/reboot of secondary node to prevent auto failover when file share is unstable?

In a 2 node FCI cluster with file share witness, assuming the file share is unstable (inaccessible) due to network issues. Case 1: File share is down (inaccessible) and during this time I patch/reboot ...
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Does cluster go down if one of the node is restarted manually and the file share witness is unstable?

I am exploring the 2 node cluster with file share. The example is as shown here: https://docs.microsoft.com/en-us/azure-stack/hci/concepts/quorum#two-nodes-with-a-witness Majority is 2/3. So when ...
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What is the way quorum majority is decided in FCI with file share?

In WSFC FCI with 2 nodes and file share, each node participates in a heart beat. The file share is a voting witness, and connectivity from any node to that share is counted as an affirmative vote. ...
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What is the list of alerts to be configured for sql server 2019 to monitor general/fci/ag errors?

I have configured the following alerts on sql server: https://www.brentozar.com/blitz/configure-sql-server-alerts/ I would like to have a list of any more error codes so that I can get alerted about ...
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What is the specific error to look for that guarantees wsfc initiated either restart or failover?

I am looking at sql server error log and the cluster log (cluster.log) file for each node in the cluster. I can see couple of errors scattered around like failed a periodic health check on file share, ...
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Why can't I see witness in the failover cluster manager snap-in?

SELECT * FROM sys.dm_hadr_cluster_members This query shows me 2 nodes and 1 file share witness. However, when I open the wsfc cluster manager snap-in, then click on Role, select the role, I cannot ...
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Database stuck in a read only state when testing a DR scenario with a multi-subnet SQL Server Always On AG, how can I get the db in a healthy state?

I am testing a disaster recovery scenario with azure VMs. I have sql servers deployed across 2 regions joined together via Always On availability groups sitting on top of a multi-subnet WSFC. When I ...
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Split Brain scenario Always on Availability group

Due to maintenance our primary site will be offline for few hours. I have an availability group where there are 2 nodes at the primary site and one node at the DR Site. Since the Primary site will be ...
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Why automatic failover does not occur when I turn off SQL Service in SQL Server Failover Cluster Instance?

I faced unusual behavior associated with automatic failover so that automatic failover does not work in the case of turning off SQL Server service. It seems that clustered disks are still remaining ...
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Is it possible to use 2 Heartbeat nics in SQL Failover Cluster ? (One for local servers, one for DR servers)

We have a 6 servers MSSQL Failover-cluster setup, 3 servers on each datacenter, where all 6 servers use a vlan set on a Cross-datacenter network for the heartbeat. So in case this line fails between ...
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SQL Server 2 node availability group - deleting secondary server, to be replaced later

I found Questions regarding removing a secondary node from an availability group with Tony Hinkle's answer, but I'd like to get some clarification on 1) removing the databases from the AG, 2) removing ...
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Postgresql as clustered role in Windows Failover Cluster

I am looking to implement a Highly available postgres cluster with automatic failover in a 2 node Windows cluster. Can we configure it similar to active passive SQL Server FCI with shared storage ...
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AOAG Cluster Role Went Failed State

We have 4 node majority AOAG failover cluster, Currently the role went to failed state when we are trying to restart the role manually again the role is going to failed state. Error 1 in event log ...
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Updating DNS on Availability Group database servers

We have always on availability group that spans across different data centers. Our network team has decommissioned some DNS servers and those servers will need to be updated with the active ones on ...
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Restoring secondary backup files on primary server in sql server

I want to restore log backup file on copy-only full backup in restoring mode on primary replica server these backups were taken from secondary replica . I took copy only full back up on secondary ...
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Migrating from old AlwaysOn Availability Group to new AG cluster but keep ip addresses

We want to migrate our SQL Server 2012 on server 2012R2 to SQL Server 2019 on server 2016 and keep the ip addresses but change hostnames. i can not change the name of listener and ip addresses from ...
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MariaDB run a new cluster while keeping an old cluster running

I currently have a 5-cluster mariadb galera set up. Two of the servers are in the cloud while three of them are locally hosted. I kinda want to start the three on premise servers to act as a separate ...
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Does a read-write-split on your galera cluster still make sense when running the servers on the same (private) cloud environment?

I know about the claims that a Galera cluster should/might perform better in a lot of cases whenever a read-write-split is set up, so there are dedicated read and write hosts in the cluster. This ...
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3 Node WFCS - How to automatically FO to DR?

I am planning to implement a two-node Windows Server Failover Cluster (WSFC) for SQL Server Always On Availability Group in our main site, and the third node in our DR site. All application clients ...
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Can Availability Group be configured in a below structure?

I have Production and DR clusters as depicted on a picture below. My question is whether there is a way to configure Availability Group from datacenter1 to datacenter2? I tried to configure regular ...
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Does AOAG needs a Windows failover cluster?

I'm reading some windows docs about AOAG and I got confused: Always On availability groups, the high availability and disaster recovery solution introduced in SQL Server 2012 (11.x), requires Windows ...
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Any idea what Virtual Machine Cluster WMI is for?

We have a Windows Failover Cluster to host our SQL Server Availability Group. We have a resource that popped up that no one recalls creating named "Virtual Machine Cluster WMI". We have ...
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Procedures to safely perform SQL Server Always On database cluster failover during Updates & Patching?

I need some steps and guidance, to perform the Microsoft Cluster Failover (MSCS 2016) for my SQL Server 2017 Enterprise Edition – Always-On 2x nodes. This is to perform the Windows Server updates that ...
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SQL Server 2017 AlwaysOn Failover Cluster issue

I have 2 Windows 2012R2 VM's running on Vmware ESXi 7 with VMDK's as the SQL disks. I have a SQL 2017 AlwaysOn Cluster running on Server 2012R2. there is no any running backup (SNAPSHOT) PROD : 10....
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How to Tune MariaDB Database System With Right Parameters

I have a MariaDB Galera 3-Node Cluster as the DB system but since I built, it is working with the default parameters. I only changed the parameter as max_connections=3000. It has been about 6 months ...
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Intermittently failover of my SQL Server resources on Windows Server 2016

I have 2 Windows 2016 VM's running on Vmware ESXi VMware ESXi, 6.7.0, 17700523 with VMDK's as the SQL disks. I have a SQL 2017 AlwaysOn Cluster running on Server 2016. Basically everything is pointing ...
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Can I try SQL Server BIG Data Cluster for free?

I can not find information about test SQL Server Big Data Cluster in a development environment. We have some AKSes and would like to try installing SQL Server Big Data Cluster. Is it possible to do it ...
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Where Should I Install Galera Load Balancer? On Cluster Nodes?

I want to install Galera Load Balancer for my 3-Node Galera Cluster, but where should I install the galera load balancer? Can I install on the cluster nodes or should I build a new server for galera ...
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SQL Server 2019 Always On - Ensure that cluster name object (CNO) is granted permissions to the Secure DNS Zone

I have here a SQL Server 2019 Always On with a lot of errors like this one: 2 nodes configured in a cluster with file share witness. Cluster name: SQLCLS Listener name: SQLLSN Event: Cluster network ...
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What is the minimum hardware requirements for SQL Server Big Data Cluster?

I am in process of making POC and would like to test SQL Server Big Data Cluster solution. My first idea is to host it on my local computer and test it but I am not sure If it possible. In found ...
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Can we add FCI to AG or a single instance from FCI to AG?

I am exploring FCI and AG. In FCI we can have 2 nodes that share the same SAN storage. And failover results in the other node starting up. Where as AG is for a set of dbs. This question is about the ...
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Always On Failover Cluster Instances (FCI) on existing SQL Server

I have launched three EC2 Windows_Server-2019_SQL_2019_Standard instances. How can I implement Always On Failover Cluster Instances (FCI) on these existing SQL Servers. I can only find details like ...
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How to setup Network in Desired State Configuration for SQLSetup - Action = "InstallFailoverCluster"

I am looking to setup the network addressing correctly. Configuration SQLInstall { node localhost { SQLSetup 'InstallSQLClusterNode1-2019' { Action = 'InstallFailoverCluster' . . . ...
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Why is the FILESTREAM data not accessible, after AG listener is created?

I'm having a hard time figuring out why my app can't access filestream data, after we enable AG listener. Background info: Initial environment: APP Server Web Server IIS Windows Server 2012 R2 DB ...
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SQL Sever Alwayson - Increase the WSFC failover threshold

Im trying to simulate the Failover in my SQL server 2017 alwayson by stopping and starting the SQL server service. It worked 2 times, but after that, the failover is not happening, It showing an error ...
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