15
votes
PostgreSQL High Availability/Scalability using HAProxy and PGBouncer
Your existing configuration of HAProxy -> PGBouncer -> PGServer approch is better. And that only works.
Here is the reason: HAProxy redirects connection to different servers. this results in MAC ...
- 406
11
votes
By Mistake Deleted AlwaysOn Availability Database from live Production Server
It is not possible to delete a database that currently resides in an availability group. It is also not possible to restore over top of it while it remains in the availability group. Thus, this ...
10
votes
Accepted
Always On FCI vs Always On Availability Groups
What is the advantage of Always On Failover Clustering vs Always On Availability Groups?
The main advantages given 2012->2017 for an FCI is:
No instance level metadata or objects required to be ...
- 246
10
votes
What is the best option for High availability on a data warehouse?
Most data warehouses are in Simple recovery model, and most true HA solutions require Full recovery (AGs, Mirroring). The minimum for Log Shipping is Bulk Logged, but that's not really true HA since ...
- 38.8k
10
votes
Accepted
Avoid downtime of Microsoft SQL Server during restarts
If you have a running query or an open transaction, SQL Server doesn't have a way to move that query or transaction over to another server.
When your SQL Server instance (we'll call Instance A) ...
- 42.7k
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, ...
- 5,472
8
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 ...
- 69.7k
8
votes
High Availability SQL Server
A solution that will work with SQL Express would be ideal, SQL
Standard is fine, but I dont want to have to upgrade to SQL
Enterprise.
If you want something straight out of the box, that's going ...
- 30k
8
votes
Accepted
Does a replica set with only two machines make sense?
If a primary member unexpectedly dies, the secondary one won't elect itself the new primary anyway, since it won't have the majority (which is two in a replica set of two machines).
This is correct. ...
- 10.2k
8
votes
Accepted
Always On Primary Replica On Prem, Secondary Replica On Azure
We only want to have 2 replicas, one on-prem and one on azure. Is this possible?
Yes, it's possible. There are extra items you'll want to think about such as having a domain controller (if ad-...
- 30k
7
votes
Accepted
What reason could cause AWS RDS connections to spike
If you run show processlist; it'll show you all the connections that are running against your DB.
Running show status like 'Conn%' can show how many connections are active
You may think that a high ...
- 2,061
7
votes
Accepted
Adding indexes to production MySQL database without downtime?
If you wanted to add indexes to a live table, there are two major approaches:
APPROACH #1 : pt-online-schema-change (Preferred Choice)
This tool is spectacular. It will create a temp table for you and ...
- 182k
7
votes
Accepted
SQL Server AlwaysOn Availablity Group Automatic seeding
You should be able to see the reason automatic seeding didn't complete by looking in the SQL Server error log from the time period where you created the AG (on both the primary and secondary replicas)....
- 29k
7
votes
Accepted
Why putting SQL Agent offline caused WSFC to fail over on passive node?
If you look in Failover Cluster Manager, if you select the role for the Failover Cluster Instance (FCI) Role, then select the "Resources" tab at the bottom you'll see that the role is ...
- 16.1k
6
votes
Accepted
SQL Server Always On or Mirroring & Log Shipping
If you were referring to Database Mirroring when you say mirroring (as opposed to SAN mirroring), then don't. It has been deprecated since 2012 now so it is a potential candidate for complete removal ...
- 1,433
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 ...
- 42.7k
6
votes
AlwaysOn AG versus FCI
In general, FCI is more beneficial compared to AG because of various reasons already mentioned above. Of course, 2-node FCI is completely great but should not be built on top of storage spaces direct ...
- 161
6
votes
What reason could cause AWS RDS connections to spike
In your RDS, first check all IOPS metrics.
RDS provide a certain quantity of IOPS, and if your RDS Instance have 10GB SSD, probably your IOPS quantity is 100 IOPS (default), this value increase ...
6
votes
Accepted
Estimated recovery time and REDO queue size related to DB up time
Estimated Recovery Time is how long SQL Server thinks it will take to run the recovery process required to bring the database into read-write, usable state. 4600 seconds is a LONG TIME. You should ...
- 69.7k
6
votes
SQL Server Connection String - MultiSubnetFailover True or Yes?
Are both "Yes" and "True" supported? Or does it vary by driver? If the latter, is there a list of which drivers support which syntax?
Every driver has their syntax. In the first ...
- 30k
5
votes
Accepted
Mongo CP, Cassandra AP?
C stands for eventual consistent. Correct ?
Consistency in the CAP theorem is referring to strong consistency where every read receives the most recent write or an error. By default MongoDB drivers ...
- 10.2k
5
votes
Accepted
MongoDB stepDown fails in a PSA Architecture
There is No electable secondaries because priority of secondary node is set to 0 (see rs.conf() in the original post. Thanks to Mani for his suggestion!).
I updated priority (and votes) for lxc-...
- 2,328
5
votes
Accepted
HADR_SYNC_COMMIT waits on SQL Server
I wanted to say kudos for diving in and investigating using XE, that's definitely a correct step in the eventual solution. Having said that, it's unlikely we're going to be able to directly help in ...
- 30k
4
votes
Postgres database zero down time production deployment
Answer originally left as a question comment.
For zero downtime during tables refactoring, we create new tables along with old ones, and switch in small steps.
From Developing Low-Maintenance ...
4
votes
PostgreSQL High Availability/Scalability using HAProxy and PGBouncer
I have to disagree with the answer provided by donatello.
You see, if your application doesn't manage DB connections using a local pool, it will create a new connection each time it needs to query ...
- 41
4
votes
SQL Server Database Mirroring is going to die. How can I guarantee high availability now?
Basic Availability Groups available in Standard Editions of SQL Servers 2016 forms a like to like replacement of Database Mirroring and has exact similar features.
Both available for Standard ...
- 395
4
votes
Accepted
Apply SP3 on SQL Server 2012 AlwaysOn AAGs
Before an upgrade, you should:
Perform a full backup of every database
Try a manual failover. Make sure the AG fails over a Synchronous replicas and that the synchronization state of the replicas is ...
- 10.1k
4
votes
Accepted
SQL Server 2014 - AlwaysOn HA - Always Synchronizing
Since you have configured AlwaysON as Asynchronous, it will be in synchronizing state.
Should it say Synchronized at some point?
If you want to do a planned failover, you should alter your ...
- 62.1k
4
votes
SQL Server Always On or Mirroring & Log Shipping
I would recommend you to use Always on availability group for server reasons.
Database mirroring is deprecated as of SQL Server 2012 and will be removed on the future versions, so it is better to ...
4
votes
Automatic Failover or Database Mirroring?
What you're describing sounds like Microsoft Sql Server HADR commonly called AlwaysOn Availability Groups. It combines traditional Windows clustering with Database Mirroring to allow you a primary ...
Only top scored, non community-wiki answers of a minimum length are eligible