19
votes
Accepted
Is "AlwaysOn" not always "Always On?"
You have a bunch of different questions in here.
Q: What is the "Always On" thing?
Microsoft uses that brand name (which was written without a space before 2016) to describe two different features:
...
- 43.2k
10
votes
Accepted
Why is there automatic failover for HA and manual failover for DR?
It is tricky with generalizations and simplifications. However, here's an attempt:
My feeling is that HA generally is closer geographically. In such cases it is more realistic to use synchronous ...
- 18k
10
votes
Accepted
Availability Group - how much data was lost after forced failover
Go to SSMS
Object Explorer
Expand Always On High Availability
Expand Availability Groups
Right click your AG
Select Show Dashboard
In the dashboard, above the list of AG databases and their status, ...
- 5,964
9
votes
Accepted
Always On AG is Down when service is stopped
It could be the issue described in INF: AlwaysOn – The secondary database doesn’t come automatically when the primary instance of SQL Server goes down by Arvindh Kalidasan - Support Engineer, ...
9
votes
Availability Groups automatic failover is not so automatic
You have a quorum issue in this setup. There are only two participants in the cluster:
SQL1
SQL2
If SQL1 goes down, there's no way for SQL2 to know that it should be the primary. For all SQL2 ...
- 29.8k
8
votes
Why is there automatic failover for HA and manual failover for DR?
This is going to change wildly based on each business's tolerance for data loss and recovery times. But, here are my thoughts on the matter.
The SQL Servers do not live in a vacuum and our HA and DR ...
- 9,244
7
votes
Restart the active node services without failover
Use the Failover Cluster Manager application to manually stop the services.
This tells the cluster you are intentionally shutting down the service, so it won't attempt to bring it back up on another ...
- 70.5k
7
votes
Accepted
How long does a failover for SQL Server Availability Groups take?
Personal observation from experience with both FCI and AG failovers, with reasonable high volume transactional system (40k trx/sec). For each consider 6 databases ranging in size from 500MB to 4TB in ...
- 4,043
7
votes
Accepted
How is ‘tempdb’ getting used when Always On Failover happens?
Tempdb doesn't move when an AG failover occurs. Each replica is its own standalone instance. Each has its own tempdb. Queries will break during the failover. Once the application reconnects after the ...
- 5,986
7
votes
Always On Failover Clustering vs Always On Availability Groups
To start with there is nothing called as Always On or Always ON availability groups it is simply called as Availability groups.
Always On Clustering and Always On Availability Groups are 2 ...
- 19.1k
7
votes
Accepted
History of cluster failover
Is it possible to get a history of when a cluster failed over and which node became the active node?
That depends on how your define "history". There will be, in the cluster log, system log, and ...
- 35.6k
6
votes
Automatic failover support on SQL Server having only two servers
For automatic failover, you need a tie-breaker.
Otherwise, what would happen when the two servers had a network split and couldn't see each other? You wouldn't want them both automatically promoting ...
- 43.2k
6
votes
Why is there automatic failover for HA and manual failover for DR?
Because in a DR scenario you need to check what really happened. E.g. your DR site loses contact with the primary. Should it activate? Well the primary might actually be fine and someone’s just put a ...
- 11.2k
5
votes
Reaching SQL Server AlwaysOn HA listener from the Internet
It's generally considered a really bad idea to make your database accessible from the internet.
Making the database accessible from the public internet is a HUGE security risk. It's easy to port-...
- 16.3k
5
votes
Stopping SQL Services on Active Node
When configured as a Cluster in Windows, you need to control the SQL Server Services from the Failover Manager, not SQL Server Configuration Manager. In Windows Failover Manager, you can fail the ...
- 511
5
votes
Accepted
In 2-node cluster using failover with Dynamic Quorum, is Witness needed?
Dynamic quorum basically dynamically adjusts votes depending on available servers.
Each time when one of nodes goes down, dynamic quorum will remove the vote from that node.
In your scenario you have ...
- 1,064
5
votes
Accepted
Longer time to bring SQL online after node failover
Most likely your problem is caused by the databases going through recovery to redo or undo transactions that haven't been hardened to data files.
Avoid recovery all together
Before doing planned ...
- 16.3k
5
votes
Accepted
Why automatic failover does not occur when I turn off SQL Service in SQL Server Failover Cluster Instance?
The Failover Cluster Manager is THE tool for managing the services protected by the cluster, so I believe it's not supposed to fail over the service if the administrator chose to stop the service ...
- 5,926
5
votes
Failover time after SQL Server patch
After patching the passive node and rebooting it, we've tried to failover to that node. But surprisingly it took ~ 10 minutes to start the SQL Server service which hanged on change pending state.
...
- 35.6k
4
votes
Accepted
Is an automatic failover to the primary replica of a readonly replica in an availability group possible?
This is covered in the documentation: Configure Read-Only Routing for an Availability Group (SQL Server), but for this approach to work, you will need to configure your read only routing URL on both ...
- 2,989
4
votes
Adding secondary replica from different subnet for AlwaysON
IP address for each subnet. Documented here: https://msdn.microsoft.com/en-us/library/hh213080.aspx#Prerequisites
- 674
4
votes
Accepted
MySQL H.A with automatic failover
Galera == PXC == MariaDB w/Galera -- These are close to the same.
For HA, you need 1 (or more) node in each of 3 datacenters. (Think earthquakes, tornados, floods, even datacenter outages -- which do ...
- 79.4k
4
votes
Who or what initiated the failover
What we would like to also see in the email is WHY and/or WHO.
Then you have quite a good bit of development work ahead of you. Seriously.
Everyone asks this same question, but it is not an easy one ...
- 35.6k
4
votes
Accepted
MongoDB failover when master is stuck on IOWait?
A closely related question is discussed extensively in the comments on SERVER-14139, a bug report against filed against mongodb. To summarize, it is not feasible to build a fully general hang ...
- 56
4
votes
Accepted
Can auto failover cause split-brain? (SQL AlwaysOn)
This following from Microsoft seems to indicate that only a person with SA, doing something stupid can cause it.
Yes, or doing completely unsupported things like using DSFR on a fileshare witness. ...
- 35.6k
4
votes
Accepted
Edition upgrade on SQL Server failover clustered instance
No, unlike Service Packs and Cumulative Updates where you're responsible to keep the bits in the same state across all nodes, the Edition upgrade applies to both nodes at once. I applied it myself to ...
- 56
4
votes
Failover strategy for SQL Server 2016 Standard Edition
Separate from your Replication solution, could use a Failover Cluster Instance or Basic Availability Group for HA of your publisher.
Or, if you have a stomach for obscure replication solutions, you ...
- 47.6k
4
votes
SQL Server Always-On Availability Groups LeaseTimeout
If you'd like to know why, the answer will be in the cluster log. If you need help looking over it, please upload the primary node's (at the time) cluster log.
Clustering makes the decisions when it ...
- 35.6k
4
votes
How to maintain a query that runs forever?
It would be easier to mod the script so that it writes out either the last value, or a value every n times so that you can restart the script with the last known value in case of failure.
Linux ...
- 134
4
votes
Accepted
How to maintain a query that runs forever?
1st thought
You have an XY Problem. You need to use an algorithm that allows you to restart from a specific point.
Code Review
Dividend.num <=@endnum exists in two places.
Get rid of the 2nd one
...
- 4,839
Only top scored, non community-wiki answers of a minimum length are eligible