Availability Groups on Andy M Mallon - AM²

AG secondary is out of sync for hours after index maintenance

Tue, 21 Feb 2023 13:17:04 -0500

Question

We have a 3TB OLTP database running Siemens Opcenter MES software at one of our manufacturing plants in China. This is setup in an Always-On Availability group with one secondary node. As this is a manufacturing plant, we are only provided 11 1/2 hours every two weeks to run index maintenance when the plant is not running production. We use Hallengren scripts to run this index maintenance.

Are Basic Availability Groups a reliable HA solution without integrity checks on the secondary replica?

Tue, 26 Oct 2021 16:21:08 -0400

Question

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 checks on secondary replicas.

Suppose that we haven't failed over in months. In our case, that seems to imply that we haven't run DBCC CHECKDB for a long time on any of the databases on the secondary. There could have been a storage corruption issue that occurred months ago that we still don't know about. If a disaster occurs on the primary replica and we fail over to the secondary, we might end up with the production application pointing at corrupt data.

Stop using sp_hexadecimal & sp_help_revlogin

Tue, 06 Jul 2021 09:00:52 -0400

Caterpillars transform into beautiful butterflies to realize their full self, much in the same way CONVERT() changes binary into beautiful hexadecimal strings.

Since I started at Stack Overflow, I’ve had the chance to see some of the interesting challenges with running our databases at our scale.

Always On Synchronous Commit Mode With Large Delays

Sun, 18 Oct 2020 11:37:09 -0400

Question

For SQL Server Enterprise's Always On availability groups in Synchronous Commit mode, is there some amount of latency that can't be exceeded? For example, can it work between very distant data centers, such as between the US and Europe?

Multi-subnet availability group, with mixed MultiSubnetFailover support (Part 2)

Tue, 06 Oct 2020 08:00:55 -0400

In yesterday’s post, I showed how to configure an availability group (AG) to use the RegisterAllProvidersIP=0 when you can’t get clients to connect using the MultiSubnetFailover=true connection string attribute.

I mentioned that you have to make some trade-offs when you set RegisterAllProvidersIP=0, and included this comparison:

Multi-subnet availability group, without MultiSubnetFailover support (Part 1)

Mon, 05 Oct 2020 09:00:48 -0400

As a DBA, we have the opportunity & responsibility to build highly available database platforms for use by applications & users. Even if you are a DBA at a small company supporting databases for only internal applications, we are usually still responsible for providing databases as a service for application teams. Sometimes, in order for us to provide the best service, we need application teams to do some work to make use of the super awesome thing we built. And sometimes, getting application teams to make that change isn’t easy, or isn’t fast, or isn’t even possible.

Replication latency when an Availability Group replica is offline

Mon, 04 May 2020 10:02:52 -0400

Assume you have configured a transactional replication publisher, which is part of an availability group (AG). Now, you have an asynchronous secondary AG (or mirroring) replica that is offline. Perhaps this is a DR node, and you are doing patching or other planned maintenance on that DR node, with it intentionally offline.

Testing as another user...without their password

Wed, 18 Dec 2019 11:50:35 -0500

This guy doesn't have Elvis's password and is still able to impersonate him. As a DBA or SQL Developer, you've surely encountered a scenario where something worked for you, but not for another user. DBAs usually are part of the sysadmin role, or have a collection of powerful permissions. If I run code as myself, I will *never* have permissions problems because my account is sysadmin. If I want to ensure permissions are correct, I need to run the code as the less-privileged account.

Can you try now?

I honestly don’t think there is a more frustrating experience than getting into the feedback loop of making a permission change, and asking the user if it works, and when it doesn’t work, you try another change, and ask them to try again, and when it doesn’t work, you try another change, and ask them to try again, and when it doesn’t work, you try another change, and ask them to try again, and when it doesn’t work, you try another change, and ask them to try again…

Copying SQL Server settings to new server

Thu, 17 Oct 2019 13:26:20 -0400

Question

We are a small business using a single SQL Server 2014 instance as our main data platform.

We now need to set up a second instance (2017) to hold additional data - this is to be standalone, ie not replicated or actively linked to the main server.

Configuring the distribution database in an Availability Group

Mon, 08 Apr 2019 08:00:23 -0400

I 💜 Replication

Starting with SQL Server 2017 CU6 and SQL Server 2016 SP2-CU3, you can now configure your distribution database as part of an Availability Group (AG). Up until now, your distribution database could only be part of a standalone instance, or failover cluster instance (FCI). In this first round, there’s a pretty big list of limitations & restrictions. In fact, you’ll notice that the “supported scenarios” list is shorter than the “limitations or exclusions.”

Configuring Replication with Availability Groups

Fri, 23 Feb 2018 10:00:41 -0500

I fancy myself more of a Jedi, but I appreciate the Empire's dedication to replication

I’ve used replication and Availability Groups together before. Replication works great with an AG as both a publisher or a subscriber (though, not as a distributor–you can’t add the distribution database to an AG). I was surprised when I recently ran into a problem configuring replication on a database that was in an AG.

SQL Server FCI won't start after OS Upgrade

Thu, 06 Jul 2017 22:25:48 -0400

Question

I have a two node sql server 2008 r2 cluster that we just did an OS upgrade from windows 2008 r2 to windows 2012 r2, the OS upgrade was done in place so the SQL Server Installation stayed in tack. The cluster role won't come back online saying it's couldn't find any IP address that this instance depends on.

Spread workload with always on high availability groups

Tue, 27 Jun 2017 14:04:54 -0400

Question

I am wondering if it is possible to split up a very large query to have parts of it done on the secondary read only servers, or If this feature only allows me to run separate queries or scripts on the secondary servers. I would also like to know if anyone is using AlwaysOn High availability groups for this purpose, how is it working for you?

Transaction Replication on AlwaysOn

Mon, 17 Apr 2017 22:21:43 -0400

Question

In our AlwayOn environment I have two SQL servers 2014 Ent.edition (SERVER A, and SERVER B). I setup a transaction replication for [database A ], pointing to listener which shouldn't cause any issue if a failover happened. Tested, worked just fine after a failover, but when I shut off one of the servers in AOAG ,in test environment, replication stops working. There is no error on the replication monitor. For testing purpose,I have inserted few records on the database it works fine on AOAG, but on the Subscriber the data modification is not replicated until I bring up the other server. Once the server is up, then the replication start to work. I'm pretty sure, I might be missing something, this can't be this way by design.

When setting up an AlwaysOn Availability Group, should the master database be one of the "Availability Databases"?

Wed, 12 Apr 2017 17:44:16 -0400

Question

I just got a Sql Server 2016 Availability Group setup (A Primary, a Syncronous Secondary and a Async Secondary). I have five databases on the servers.

I setup an application to run queries against the server (using Entity Framework with a "failover partner" connection string.)

Risks of manual failover in Always On Availability Groups

Thu, 09 Feb 2017 19:11:24 -0500

Question

In my environment, I have SQL 2014 with Always On Availability Group for databases in asynchronous with manual fail over.

We have 1 primary and 2 secondary replicas--secondary1 and sec2.

I have to do failover from primary to secondary1. I know some data loss will happen as it is a forced failover.

AlwaysON Migrate from 2014 to 2016

Thu, 01 Sep 2016 19:19:24 -0400

Question

I have like 20 Listners on 2014 with approx 500 DBS,

what is the best way to migrate these with least downtime, effort

My idea is: Stop access Backup dbs Start restore dbs While restore is running: Drop AOG on 2014 Create it on 2016 Done

Podcast: Mirroring, Availability Groups, Replication, and Log shipping

Wed, 31 Aug 2016 09:29:03 -0400

Have you ever wondered what the best option is for making your data available in your environment? I was asked by Carlos L Chacon (blog|twitter) to be part of a panel on his podcast for an episode discussing some of the options–availability groups, mirroring, log shipping, and replication. We cover each topic in detail and explain the positives and negatives of each one.

What is the benefit of having multiple databases in the same Availability Group vs single AG per database

Mon, 08 Aug 2016 06:11:50 -0400

Question

We are planning a migration from current mirroring architecture to Availability Groups for several databases. For every Database we have defined the primary/secondary replica configuration.

The question that I'm unsure is: do we need to group the databases with the same primary/secondary configuration into the same AG, or use one AG per Database. What are pros&cons of having individual AGs vs AG with multiple databases? Is there a best practice to determine if a database needs its own AG or can be combined with others? Any performance or failover advantages?

ReportServerTempDB in AlwaysOn Availability group

Mon, 11 Apr 2016 16:01:57 -0400

Question

ReportserverTempdb logfile is 6TB in size and growing and I need help. I am supporting a huge reporting server farm and the client wants reporting services to be in AlawysON Availability group(AAG) and we configured reportserver and reportserverTempDB on in three node Primary replica, synchronize Secondary replica and DR in a different location with manual synchronization. Microsoft recommends reportservertempdb to be in simple recovery mode but if you add it to AAG that is not an option. Does anyone has reportservertempdb in AAG? I would like to advise customer to take reporservertempDB out of AAG and we can just keep the copy of the reportservertempdb on each node and that should be fine. Please advise.

How to configure SSIS in SQL Server AlwaysOn

Wed, 30 Mar 2016 05:40:07 -0400

Question

I have AlwaysOn Availability Group setup for my SQL Server. Now I would like to configure SSIS. How do I do it? Below link provides some information but since I am not DBA it's difficult to understand this article:

DROP TABLE Bug on Filestream Garbage Collection

Tue, 08 Dec 2015 15:36:05 -0500

FILESTREAM is not a particularly popular feature of SQL Server–if you’re using it, you are in the minority. If you have a database with filestream in an Availability Group, then you’re REALLY in the minority. At my 9-5, this is being done, and it’s apparent that this combination of features isn’t a robust combination.

Will Transaction Log backup to Nul break Always On Availability Group configuration?

Mon, 31 Aug 2015 23:08:35 -0400

Question

Imagine we have two nodes participating in SQL 2012 AO. This is a test instance. During one of the index rebuild operation the log was grown up really big (250 GB). We are unable to back it up due to space constraint. What if we backup the Tlog to Nul (just to shrink it down) – will that break Always On?

Using SQL Agent MSX for Availability Groups

Tue, 07 Jul 2015 00:22:00 -0400

Availability Groups (AGs) are all the rage these days. Every SQL Saturday, every local Users Group, bloggers and DBAs everywhere are all talking about how cool they are. There's a lot of talk about how AGs provide a compelling alternative to Failover Cluster Instances (FCIs). The cost (nothing is free, of course) is that with AGs, you have non-contained objects that you need to manually keep in sync between nodes.

A lot has been said and blogged about syncing non-contained objects. Here. Here. Here. Here. And plenty of other places.

SQL Server 2012 always-on backup, full vs copy-only

Fri, 25 Apr 2014 19:19:45 -0400

Question

I need a quick clarification on copy-only backup vs full backup as it pertains to transaction log numbering and restore if required.

I have SQL Server 2012 setup with always on for multiple databases. The availability groups are setup with preferred backup on replica.