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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HADR_SYNC_COMMIT waits on SQL Server
Let me preface this post by saying that I am missing a few events from my trace, but I have since added them for the next time this occurs.
Lately we have been seeing weird spurts of HADR_SYNC_COMMIT ...
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High Availability postgres db cluster with Patroni and Etcd
I am building a HA Postgres db cluster with one master and multiple slaves. Please look at the below points and correct me if I am wrong:
For each slave node, I need to use pg_basebackup to sync and ...
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Failed to start patroni
I am trying to configure patroni and etcd. Etcd is working fine, but patroni is failing to start. I have 3 servers, I have installed patroni and etcd on each server. When I try to start patroni on ...
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Configuring SQL Server 2019 Always ON between 2 Azure reqions
I have SQL Server on Azure VM which I want to replicate across a separate region. I will only be using 2 servers, each in a separate region. I have the following questions as I need to clear all ...
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What is the risk of deleting millions rows from an offline table?
I'm a junior DBA for a medium-sized company that helps merchants exchange money during sales. Our services operate 24/7, 365 days a year, so performance and uptime is absolutely critical. We have a ...
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106
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Configuring a Failover Cluster Fileshare Witness?
I'm relatively new to high availability groups in SQL Server, and am hoping for a bit of advice on best practices for configuration. I didn't set up this configuration, I inherited it and am trying to ...
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71
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SQL Server Service Broker on a High Availability Group
I'm using a instance with Microsoft SQL Server 2016 || Enterprise Edition and I need to enable Service Broker for my database with this sentence:
ALTER DATABASE DB SET ENABLE_BROKER;
The size of the ...
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1
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Configuring High Availability for MySQL Router in a MySQL InnoDB Cluster
I've configured a MySQL InnoDB Cluster for high availability with two servers on a Windows system (Server 1: h01xxxxxxxxx1, IP: 10.xxx.xx.61, Server 2: h01xxxxxxxxx2, IP: 10.xxx.xx.71), running ...
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SQL Server 2017 HA Availability Group LSN issue
I ran across a issue I have not seen before and not sure how to correct the issue. We have 2019 SQL setup using HA AV group and the other day I had to recover to a Point in Time but as I was taking ...
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Can a user connect to multiple Basic Availability Groups via listeners?
Assuming multiple, let's say 50, basic availability groups are on the primary replica. Each AG has its own listener.
The primary replica goes down, and all the AG's fail over to the secondary. How ...
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Basic Availability Groups: can each AG share a listener?
What are the potential consequences of using the same listener for each Availability Group when using Basic AGs? Is it even possible?
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How to temporarily switch PostgreSQL to logical replication to allow major version upgrade without downtime?
We have a PostgreSQL cluster running on one master (db1) and two async hot-standby servers (db2 and db3) replicating from it. All the servers are working as a backend for a web service and all the ...
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Why is PostgreSQL data checksums not enabled by default?
According to user comments PostgreSQL data checksums have very minimal runtime overhead (both CPU and storage) but would allow (among other things) using pg_rewind for point in time recovery (PITR). ...
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131
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Ola Hallengren's Maintenance Solution script doesn't dump transactional log file to Destination
At one of our client sites, I implemented a high availability (HA) solution. However, during the backup process, I encountered an issue related to backup environment configuration. We had configured ...
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Can not Truncate the database because “secondaries has no log was added”
I am a newbie to SQL Server. I got an error when trying to truncate the database:
Database can not shrink until all secondaries have moved past the point where the log was added.
When I check the ...
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2
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SQL Server Connection String - MultiSubnetFailover True or Yes?
The MultiSubnetFailover option in database connection strings controls how the client attempts to connect to a database server, especially when multiple IPs are available.
There is conflicting ...
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SQL Sever High Availability - 3 nodes configuration
We have already configured SQL Server High Availability group (Windows Cluster grouping) with 2 different sub nets 10.x.x.x and 192.168.x.x (data center - more than 30 miles away). At present, there ...
Kyle Jamieson
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1
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Remove Databases from HA Group using TSQL - SQL Server
I am trying to automate following steps using TSQL (It is currently working fine using Manual -GUI interface of SQLServer), working on SQLServer 2022
Create a table, with columns to store DBName, ...
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1
answer
229
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Different query result in SQL Server high availability group's nodes
I have high availability group with two nodes and I ensure they have "synchronized commit" mode. So I assured they are identical in records of tables.
A developer reported a bug for ...
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255
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HA 3-Node Postgres cluster on VMs with Repmgr
We are considering a 3-node Postgres setup where 1-master and 2-standby with replication and master failover handled by repmgr and connection pooling with Pgbouncer.
Is there a way to let our ...
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702
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PgPool-II can't find the servers where the databases live (even though the PgPool is on a db server)
PgPool-II 4.3.3 Postgresql 13.9 RHEL 8.6
Postgresql is installed on FOOBARa and FOOBARb, and data is successfully being stream replicated from a to b.
Then I installed PgPool-II on a, and configured ...
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138
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Galera WAN Clustering use case, having remote nodes performance impact is not clear
In official doc Galera Use Cases for the 2nd, WAN Clustering use case I am reading the following:
"Synchronous replication works fine over the WAN network. There will be a delay, which is ...
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Galera cluster performance, node count, and where to write?
As far I understand Galera does not scale write performance, best case it does not degrade it, compared to one single server, so we use Galera for HA.
(read performance may benefit and it can be load ...
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2
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110
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SQL Server Always On - security updates without DB disconnecting from application
Our real-time communication application relies on database access, and it cannot be disconnected from the DB when running.
Recently our customer’s DB maintenance team notified us that the DB will be ...
Michal.Jan008
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1
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114
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How to reliably restore slave to master in MySQL Multi Source Replication?
I have multi source mysql replication setup configured, so I have this big server which act as a slave to other smaller server. The setup looks similar to below.
Everything is working fine— until one ...
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Multi master with some slaves vs single master with some slaves
I need some advice on architecture.
I have a national database that relies on postgres and some architectural design that involves orchestrating several components, very much similar to the picture ...
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474
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how to make PostgreSQL-13 slave node as read-write once primary node is down
I have two servers in master-slave configuration format. They are in streaming state and synchronization state is "Sync".
I also used "repmgr" to make them as a cluster in primary ...
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271
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Does further partitioning a MariaDB table require downtime?
I need to add partitions to an already partitioned table, the table has RANGE partitions by year(timestamp), but the previous admin stopped partitioning awhile ago. Now the table has grown to 4.1 ...
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2
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262
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what after WAL LSN value of type pg_lsn reach its limit
I am trying to determine the optimal Standby for automated failover based on the highest value of pg_last_wal_receive_lsn() of all slaves. But what if max_wal_size is reached, does pg_lsn values go to ...
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Can I change the password of the domain account which I used to create the failover cluster?
Can I change the password of the domain account which I used to create the failover cluster? Will it affect the cluster at all?
I have also created the Always On availability groups using that domain ...
TechAnons
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26
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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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78
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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 ...
Chaureid70
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2
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566
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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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75
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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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5
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4k
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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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444
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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 ...
chandan
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1
answer
300
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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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2
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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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290
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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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284
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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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42
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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 ...
