Questions tagged [high-availability]

High-availability technologies mask the effects of hardware or software failure, so that perceived downtime for users and applications is minimized.

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Oracle Accessing Data from Two Databases Transparently

Our Oracle version is 19c We have a need to split our data into two separate databases. Most recent data will go into DB_1. Older data will go into DB_2. We do have Webserver tier. One options is to ...
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Oracle DataGuard between 11.2.0.4 (primary) and 19c (physical standby)

Our production database is on 11.2.0.4. It needs to be upgraded to 19c. Can I setup physical standby which is at 19c and keep it in sync with primary ? Thereafter - during a weekend maintenance, the ...
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How to extend Distributed availability groups to another datacenter

Actually I have a Distributed availability groups with SQL Server 2016 configured like this: The endpoint are configured like this: USE [master] GO CREATE ENDPOINT [endpoint_istance2] STATE=...
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System/database design for comments/replies and upvotes at scale

Recently I started discovering a topic around "How to design db schema for storing structures similar to Instagram/Facebook/Reddit comments?". After extensive research, I was able to find a ...
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Replication from a secondary in a high availability group

We have a couple of servers in a SQL Server HA group, one acting as primary and the other as secondary. This system is working fine and fails over as expected (though this is very rare). However we ...
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SQL 2019 High Availability Stored proc issue on secondary server

I've just upgraded my High Availability environment from SQL 2017 to 2019 version 15.0.4236.7 I have same SQL Agent Jobs on both servers with a initial clause to determine if the job should run (if ...
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SQL Server High Availability Dashboard comes up blank when accessed. Is there a fix for this?

Recently whenever I access my SQL Server High Availability Dashboard, it comes up blank and I am not able to see the databases and the synchronization between the servers. Is there a solution to ...
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2 answers
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What is the best solution for synchronous sync and load balancing an InnoDB database

I'm trying to find the best setup to horizontally scale an ecommerce which is currently on a single dedicated server, but even reading some of the replies here on DBA I'm still confused on what is the ...
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which High Availability and Disaster Recovery method would be suitable for my SQL Express server

What are the considerations that would determine which High Availability and Disaster Recovery method would be suitable for my MSSQL express server? These are some of the considerations I found on the ...
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Why does FCI not have worry of split brain scenario?

SQL server AG has lease time-out to ensure there will never be a split brain scenario. Where as there is no such thing for FCI. Both AG and FCI (HA) require the windows failover cluster, but why does ...
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Always On availability group - Standard Edition

I need advice regarding Always On for SQL Server Standard Edition 2019. My question is... is that even possible and if that makes sense to use that on production? I have two servers (A- primary and B-...
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Sql server replication for HA and DR

1.)According to brent ozar's HA and DR chart,for Failover Cluster Instance - SQL Server minimum version supported and SQL Server minimum edition required is given as 'any'. Does that mean it works ...
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File Share Witness location

We have a 4 node availability group with 3 node on the primary data center and one node on the secondary data center. We want to add a file share witness and since we dont have a third data center and ...
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Removing router from MySQL InnoDB cluster

Currently I have configured 3 node MYSQL InnoDB Cluster with two routers. Is it possible to remove one of the router from cluster? what are the implications ? using cluster.listRouters() I could see ...
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2 votes
1 answer
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Availability groups across sites: what happens if severs can't contact each other but both still can reach file share witness?

I'm currently planning a new SQL Server 2019 Enterprise Edition setup with HA/DR, possibly with availability groups. Let say we have the following setup: Site A: one SQL Server instance (SQL1) Site B:...
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When queries start executing on standby server the replay lag starts to increase

I have a two servers with following specs: 8 vCPU, 32768 MB RAM, 640 GB SSD The master Postgres 13.3 database (db1) is installed on first server (Ubuntu 16.04.7) with the following config: ...
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Are Basic Availability Groups a reliable HA solution without integrity checks on the secondary replica?

We have a few Basic Availability groups in production and I've been reading about the limitations of them. I'm concerned about the following limitations: No backups on secondary replica. No integrity ...
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SQL AAG Cluster - Diagnosing Partner Quorum Failure

Recently we had a failure of our SQL Server (2016) Always On Availability Group, where our fileshare witness node was briefly inaccessible to our two nodes due to a CPU spike. We have two SQL server ...
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HADR Availability Group long sync time

I have the following problem / challenge: We operate an HA SQL cluster with several Availability Groups. In order to take full advantage of the load balancing, I redirect the SQL selects to the ...
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High Log Send Q in AG server

We have 6 SQL Server cluster all are part of AG, 1 is primary server and 5 are secondary read replicas. We are facing issue with High log Send Q size for specific database, we have 5 database in AG ...
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What is the equivalent of on prem ha dr solutions in the azure cloud PaaS and SaaS?

On prem ha dr solutions are: Log shipping Mirroring Replication FCI AG What is the equivalent of each of the above in the azure cloud PaaS (azure sql managed instance) and SaaS (azure sql ...
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Is there any sql ha dr solution that allows write to multiple servers?

I am looking for a sql ha dr solution that allows users to write to multiple replicas. Is this possible in sql server? For example: AG allows read from multiple replicas. But write only to primary ...
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Configure cluster on an existing SQL Server - to setup AlwaysOn Availability Groups

We are already having an SQL Server Enterprise Edition instance running on an Physical Server. Now to configure AlwaysOn Availability Groups Can we configure WSFC (Windows Server Failover Cluster) ...
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SQL Server always on servers reboot

I have the below set up for availability group : Always on configured in SQL Server 2017: Primary is read write and secondary is read only. Both primary and secondary are configured with asynchronous ...
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3 votes
1 answer
292 views

Why putting SQL Agent offline caused WSFC to fail over on passive node?

I have 2 node Windows Failover Cluster with Quorum disk. SQL agent is NOT a resource of the cluster. I needed to enable service broker on the server; for that I need to set SQL Agent offline, run tsql ...
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Always On with multi AGs primary on each replica - Any gotcha's?

I have a bunch of Always On clusters that I manage and am really comfortable with them. I have one client who is running an Always On cluster with 2 replicas. They have 4 AG's that each have their ...
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Automatic Failover for Basic Availability Group

This will be my first project with Basic availability group so I thought would check before implementing . As per Microsoft documentation below it says we will need to have Software assurance for ...
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Implementing reconnection behavior for SQL Server always on availability group listener

I have an SQL Server 2019 Cluster with a high availability DB. I set my .NET 5.0 (using Entity Framework) app to connect to the listener, expecting that if the cluster fails over, things would just go ...
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How can i get AG dashboard values via SQL Query across all supported versions of SQL server

I am trying to ease the monitoring of availability groups across multiple SQL servers. Came across few dmvs which got me the data. But cannot figure out some important columns which i am seeing in ...
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How to configure Always ON High Availability on this infrastructure?

I have SQL 2017 Enterprise Edition What would be the best way to set up High Availability in the below infrastructure? Datacenter 1 WSFC and FCI: Node1, Node 2, Shared Storage Datacenter 2 WSFC and ...
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LISTENER_IP = ALL not working

I try to create an endpoint specifying to listen on any IP: CREATE ENDPOINT [Hadr_endpoint] AS TCP ( LISTENER_PORT = 5022, LISTENER_IP = ALL ) FOR DATABASE_MIRRORING ( ...
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Windows Failover Cluster/Availability Groups - Issues because all servers of one site where unreachable

we had some issues because of maintenance and hope someone can explain what happened. Our cluster looks like this: Site A: Node A1 (Quorum vote) Node A2 (Quorum vote) Node A3 (Quorum vote) Node A4 (...
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Estimated recovery time and REDO queue size related to DB up time

Can someone help me figure out if my understanding is correct on the below: On the AG Dashboard for my readable secondary replica I see: Estimated recovery time (secs) - 4598 REDO queue - almost 24 ...
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SQL Server: Always On Availability Group: getting Error: GetAccountToProcess failed: Cannot open database requested by the login. The login failed

When myself and our SA are testing our AO group, we are running a script that flows data into a table so we can monitor proper data. We are pointing this at our Listener: TestDBAG01, and it flows into ...
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what databases are already set up in the log-shipping, and which ones are not?

I am setting up log-shipping from server1 to server2. there are many databases on server1 and I want to automate the process. I have already done a few databases manually, while I am working on the ...
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Why does the secondary server not failover?

I hope someone can help. I will try to summarise as best as I can. We have four servers in a cluster with an AG set with Database Health Detection. Three servers are on site1 with the fourth on a ...
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Why is FCI not considered to be a DR solution? [duplicate]

FCI is said to be an HA solution. If one node crashes, it spins up the 2nd node so why is it said to not be a DR solution? There was a disaster at node 1 and node 2 picked up from there. Isn't that ...
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HA options for a VLDB

We have 2 VLDB's - 6TB (primary db, not much OLTP traffic) and 4TB (archive db). Data will be moved/archived (delete from primary and insert to archive) daily from 5 large tables. Currently this ...
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pacemaker and semi-synchronous replication

In the company I work we use a simple setup of a Primary-Secondary replication. Should the Primary break down for whatever reason, we do the switch manually. This also means, that MySQL hardly ever ...
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Alwayson fn_hadr_backup_is_preferred_replica takes a long time to return results

Our 2 nodes full sync mode Alwayson cluster has 20 databases which allocated into 4 different AG groups (9, 6, 3, 2). We set backup preference as on 'preferred secondary'. Find out that ...
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1 answer
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SQL Server Always On AG – Is a Passive Secondary Required for Automatic Failover?

It is my understanding that for automatic failover to occur in an Always On AG environment, the replicas just need to be configured with "automatic failover," "synchronous commit" ...
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1 answer
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Buffer Pool scan took 10 seconds error

Using SQL server 2017 (14.0.3381.3) with Always On High Availability environment. Getting error:"Buffer Pool scan took 10 seconds: database ID 8, command 'CHECKPOINT', operation 'FlushCache', ...
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SQL Always on Availability Groups Direct Seeding

Setting up a new SQL cluster and HA using SQL Availability Groups. SQL 2019 STD 2 Node Multi Subnet Basic AG Primary Node AWS Secondary Node VMWare on premise I am using the newer Automatic Seeding ...
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What are the available automatic failover solutions for MariaDB Master-Slave replication on Windows Server?

I am setting up a Master-Slave or Master-Master setup in MariaDB on two seperate servers running Windows Server. I also need to configure an automatic failover solution where client read requests gets ...
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Does listener gets affected when we replace secondary replica with another server in Availability Group?

I have created Multi Subnet Always On Availability Group. Now, I need to replace secondary replica with another server in Availability Group. In this case, Do I need to re-create listener? OR The ...
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what will cause a sql server AG readonly replica to stop serving readonly clients?

I understand that if a failover happens (among any nodes in an AG), then all nodes lose their existing connections. And I assume that if a primary suspends data movement, that will have no effect on ...
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behavior of a Sql Server availability group listener and a jdbc client during a failover?

i have a question about the behavior of the AG listener during a failover... when the failover happens, I realize that all the connections on both primary and secondaries are closed. if the client ...
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Archiving with hot standby streaming replication log shipping is not working

I get the following error message in my postgres logs: >LOG: archive command failed with exit code 1 >DETAIL: The failed archive command was: (ssh postgres@backupdb.com "test ! -f /var/...
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Can I use SQL Server Standard Edition as Primary and Enterprise SQL Server as Secondary node?

I have Software Assurance for SQL Server Enterprise Edition and I need to setup High Availability on it. The issue is my primary SQL Server has a Standard license. Could I add SQL Server Enterprise ...
5 votes
2 answers
665 views

Availability Group - how much data was lost after forced failover

Let's consider a SQL Server AlwaysOn cluster with two nodes in asynchronous replication. Is there any way to calculate how much data was lost after forced failover? I mean in terms of time, to be able ...
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