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.

Filter by
Sorted by
Tagged with
22
votes
2answers
5k views

What is the modern way to partition PostgreSQL across machines, when the data is "naturally partitionable"

After several years of dwelling into the "NoSQL" space, now I have a problem that is quite "relational" in its nature. Today I see data stores with quite different eyes than before. Things like Riak ...
20
votes
3answers
31k views

PostgreSQL High Availability/Scalability using HAProxy and PGBouncer

I have multiple PostgreSQL servers for a web application. Typically one master and multiple slaves in hot standby mode (asynchronous streaming replication). I use PGBouncer for connection pooling: ...
20
votes
2answers
558 views

Is there a complete list of Online operations for each SQL Server version?

As we are about to change some of the large tables in our 5TB database I found myself needing a list of the operations that can be performed online and the which require full locks to be held while ...
12
votes
5answers
17k views

SQL Server equivalent to functionality of Oracle RAC? [closed]

I did some Googling and couldn't find an answer to this question more recent than a few years ago, so I thought I'd ask. Oracle's RAC feature offers load-balancing for both read and write transactions,...
12
votes
3answers
7k views

SQL Server Database Mirroring is going to die. How can I guarantee high availability now?

The Database Mirroring feature of SQL Server is going to die: This feature will be removed in a future version of Microsoft SQL Server. Avoid using this feature in new development work, and plan ...
12
votes
2answers
5k views

Do schema changes "break" Availability Groups or are they handled transparently?

My organization is planning to adopt SQL Server 2012 Availability Groups and I am trying to understand what impact (if any) it will have on our application upgrade process. We release application ...
10
votes
2answers
24k views

What are the differences between Mirroring and Failover Clustering and when is each one recommended over the other?

What are the main differences between Mirroring and Failover Clustering? What kind of problem each one solves and in what kind of scenarios is each one recommended over the other?
9
votes
2answers
14k views

What reason could cause AWS RDS connections to spike

It's my first time using RDS on AWS, I use a t2.medium instance running MySQL Aurora with default configs. The CPU usage and DB connections is quite normal until "something" happens, which causes the ...
8
votes
2answers
2k views

Can Availability Groups replace transactional replication?

I've been looking at the new features of SQL Server 2012, and how it can help my current situation. Currently we're on SQL Server 2008 R2, and replicate two OLTP servers' databases to a single ...
8
votes
2answers
1k views

High Availability for postgresql

I'm new in PostgreSQL database. Recently our developer needed to do some upgrades in our systems. Because of that we are planning to implement some method in order to implement database failover. ...
8
votes
1answer
2k views

SQL Server AlwaysOn to run updates and schema changes in 24/7 environment

First of all i have to say that this question comes from a software engineer-perspective. Unfortunately we have no DBA so we need to administer our own databases. We have SQL Server 2012 Enterprise ...
7
votes
1answer
4k views

Does "Synchronous-Commit Availability Mode" ensure consistency between Replicas?

If one refers to the MSDN documentation, on Synchronous-Commit Availability Mode, you may read: Under synchronous-commit availability mode (synchronous-commit mode), after being joined to an ...
7
votes
2answers
2k views

What is the best option for High availability on a data warehouse?

I have a customer who have an existing 1.5Tb data warehouse and are currently planning for a complete refresh of the DW on a new environment. Their infrastructure manager has organised 2 servers with ...
7
votes
2answers
2k views

SQL Server replication for off site copy

We have our Primary SQL Servers in-house (15 primary servers at the moment (500 databases approx overall), most of the servers have hex core processors). These are mirrored to other backup servers in ...
7
votes
1answer
2k views

Recovery time effects of Availability Groups

We did different kinds of basic Tests and AlwaysOn passed in many tests. We finally did a heavy write test for AlwaysOn and it gave surprising results. The actual Test details are here, the goal is ...
7
votes
1answer
220 views

Multi-homed SQL Server with High Availability Groups

We have two servers (SQL-ATL01, SQL-ATL02) that make up a Failover Cluster, each running as part of a SQL Server High Availability Group (HAG). Each server has two network cards. One is a 10Gbit card ...
7
votes
1answer
1k views

SQL Server Database Mirroring : strange client application behavior upon failover

I am putting a HA SQL server environment up based on three SQL Server 2008 R2 machines and database mirroring. I'll name them : principal.company.intra mirror.company.intra witness.company.intra ...
6
votes
3answers
17k views

How to check history of primary node in an Availability Group?

How do I see history of failovers of the primary node of a cluster? I'm trying to figure out at what point secondary node started to act as primary. We are running Windows Server 2012 with SQL Server ...
6
votes
2answers
8k views

AlwaysOn AG versus FCI

Throughout MS documentation for AlwaysOn Availability Groups (AG) and AlwaysOn Failover Cluster Instances (FCI) I see the following pattern: FCI is for HA scenarios. An AG synchronous secondary ...
6
votes
2answers
3k views

Transaction Log Truncation with Copy Only

I have a database backup job set to use full backup with the Copy only option on once daily. The copy only is on because from what I have read that is the only way to backup a database that is ...
6
votes
1answer
141 views

Where to put a database in case of IP failover?

I understand that to achieve some level of availability of an online application it is possible to organize an environment with a redundancy using an IP failover mechanism and switching between ...
6
votes
3answers
2k views

SQL Server Always On Node and File Share Majority

I am looking for some guidance on architecting our SQL Server 2016 SP1 Always On Availability Groups HADR solution on Windows Server 2012 R2. We have a primary site A with a primary replica and a ...
5
votes
2answers
465 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 ...
5
votes
5answers
2k views

Setting up a Redundant Sql Server 2008 Configuration While Retaining High Performance and Minimal Downtime

We have a situation where we are moving to a new hosting facility and are attempting to configure our new database environment. However, none of us are formal DBA's so a lot of what we are doing is ...
5
votes
2answers
4k views

Restart the active node services without failover

On a 2 node Windows Server Failover cluster configuration, how do I restart the SQL Server services without failing over to the other node?
5
votes
2answers
2k views

Failover Cluster Diagnostic Logs

I know there must be a simple answer to this question, but I cannot find it anywhere. Our SQL 2012 FCI have SQLDIAG .XEL files in their MSSQL\LOG folder. In some instances, these files are often ...
5
votes
2answers
6k views

Recommended distributor architecture for transactional replication?

We are planning to create a Transactional replication on 2 nodes of SQL Server 2008 R2, each node will be a publisher and a subscriber. What is the best practice in order to have this scenario done? ...
5
votes
1answer
2k views

Questions on Availability Group Readable Secondary

Recently I encountered an issue in my SQL server. Please advise the concept and mechanism behind the AlwaysOn cluster. Background: We built up a AlwaysOn cluster with 1 primary node dbs1 and 1 ...
5
votes
2answers
1k views

Replication with FileStream

I need to setup database replication (for high availability) on a database that uses FileStream. This is on SQL Server 2012 Standard Edition, so Always On or Peer-to-Peer replication is not an option. ...
5
votes
1answer
630 views

ENABLE_BROKER vs NORECOVERY

I have two nodes with MSSQL2012 which work with AlwaysOn High Availability After some crash I had to remove db from availability group on the one of the nodes. For restoration I've made backup (full+...
5
votes
2answers
641 views

SQL AlwaysOn & System Center Configuration Manager TP 4 1601

Recently Microsoft released Technical Preview 4 for Configuration Manager (1601). Per TechNet, "Configuration Manager now supports using a SQL Server AlwaysOn availability groups to host the ...
4
votes
1answer
1k views

By Mistake Deleted AlwaysOn Availability Database from live Production Server

Today by mistake deleted The AlwaysOn Availability Database from live server. Let I am explaining the Details. In AlwaysON Availability Groups, there is 2 Availability Replica. That is Primary ...
4
votes
1answer
766 views

How to determine high availability configuration is working correctly

I am in the process of setting up always on high availability clusters for the first time. Can anyone explain to me from the networking perspective after configuring the group and testing to make sure ...
4
votes
1answer
504 views

Always On Primary Replica On Prem, Secondary Replica On Azure

We want to create an Always On Availability group where the primary replica will be On-premises and the secondary replica will be on an Azure VM. I have researched and I know it's possible to do this, ...
4
votes
2answers
3k views

SQL Server Always On or Mirroring & Log Shipping

We have two data centers with a 2 ms ping time between them connected by a site to site VPN. In the primary data center we have 2 servers, in the secondary data center we have a single database server....
4
votes
2answers
11k views

Rename Availability Group and AG script

I have two questions for you guys. I really appreciate your help. 1.- Is there a way to rename an Availability Group? 2.- Is there a way to get the T-SQL statements in order to re create a ...
4
votes
5answers
2k views

Avoiding MySQL Fabric to become a single point of failure

I managed to install and configure MySQL Fabric that manages multiple MySQL Server nodes. It works very well since I tested it by connecting to the Master node directly and played with the data (...
4
votes
2answers
4k views

Does a replica set with only two machines make sense?

A lot of MongoDB tutorials, when they talk about replica sets, give examples of two machines: one originally initialized as primary, and another one originally created as secondary. As I understand ...
4
votes
2answers
984 views

Patroni : How to handle a replica which has been disconnected from primary for long time?

Let's say I am using asynchronous streaming replication with the below configuration in a 3 node cluster with Postgres 10.4 and Patroni 1.4.4 bootstrap: dcs: ttl: 30 ...
4
votes
1answer
3k views

timeline 2 of the primary does not match recovery target timeline 1

I want to create a configuration with postgresql and pgpool to get height availability (HA). I want to do this: .-----. .--------. | | W | DB | | APP |---...
4
votes
1answer
714 views

SQL Server DR, mirroring or virtualise and mirror

I have a client with a small business server 2008 Premium installation. This obviously includes SQL Server 2008 standard on a separate 2008 server. On the SQL we run several line of business ...
4
votes
1answer
5k views

MySQL Replication and High Availability

I know this might not be a very good question to be asked in this site, but I really need some helps/hints to be directed to the right path. I want to have failover strategy for 2 MySQL servers which ...
4
votes
5answers
6k views

MySQL cluster - how many hosts are needed for full HA?

I need some clarification on MySQL-Cluster (NDB) setup I want to achieve full HA but I'm low on server budget and can't afford to rent a dozen of servers for simple solution that I'm working on. ...
4
votes
2answers
783 views

Is MySQL Clustering a viable option for a DB expecting 5TB of data in 5 years?

We plan to implement MySQL Clustering.The database should support 5 years of data and expected data/year is 1TB. When we created a test enviornment with the DB size as 200GB, NDB Cluster took more ...
4
votes
1answer
3k views

Availability mode - manual failover mode, best practice for availability mode?

We don't want automatic failover for our availability group, but I have set availability mode to Synchronous, was that a mistake? The availability group runs on vmware with windows 2012R2, and I got ...
4
votes
1answer
392 views

Is there any way to add a witness without restarting the witness afterwards?

I want to add a third instance of SQL server to my mirroring pairs to act as a Witness. When I set the witness, the mirror remains disconnected from the witness and the mirror's log accumulates errors....
4
votes
1answer
3k views

MySQL: Alter Table on very active table gives "Waiting for table metadata lock"

At my work, we've recently upgraded to MySQL 5.5 and since then, have been bitten a few times by the new (and intended) behavior of metadata locking. Basically, whenever we run an ALTER TABLE ...
4
votes
1answer
4k views

Configured MySQL replication but its not working

I have configured MySQL master and slave replication setup on 5.5.x. But for some reason data is not getting replicated properly. What might be the reason? At Master: /etc/my.cnf [mysqld] log-bin=/...
4
votes
1answer
970 views

BAK files not created on Secondary or Primary

SQL Server 2014 with most DB in AG. Backup preference set to prefer Secondary. Plan 1 backup all user DBs (AG and non AG) Plan 2 backup all user DB trans logs Both .bak and .trn files were created ...
4
votes
1answer
907 views

SSIS with MultiSubnet Availability Groups

I am planning for a "multi-subnet" AG group . 2 at the primary data center in DC and one at San Jose. We are planning to test a vendor application which requires SSIS. I am planning for the SSIS to ...

1
2 3 4 5
9