I modified my RDS instance to "Multi AZ : Yes". My primary RDS instance is in us-west-1a and for multi-AZ the secondary zone is shown as us-west-1c. I wanted to verify if whatever changes I am making on my primary database are getting copied to the Multi-AZ standby database quickly.
But I am not able to understand what endpoint URL should I use to login into Multi-AZ database. I am thinking the end point URL would be different from primary. Could you please help me on this?
You do not have access to the secondary RDS instance in a Multi-AZ configuration. You just need to trust that AWS is replicating data correctly. In a Multi-AZ configuration, RDS will write to both replicas syncronously. It will not return the write request until both replicas have written correctly.
To access a Multi-AZ instance, you issue your reads and writes to the single RDS endpoint. In case of an issue, AWS will modify the DNS entry for that endpoint to point to the secondary replica. So as long as you are using the endpoint DNS record, and not caching the IP address when accessing the RDS instance, the failover process should be transparent to you with only a minute or so of "downtime".
take a look at https://aws.amazon.com/rds/details/multi-az/. You don't typically interact with the replica(s) of RDS resources directly; AFAIK ( I'm not an rds expert ) you can't do what you're describing. The idea is that RDS does that for you, automatically keeping a consistent replica in a different AZ, and providing to you a consistent DNS endpoint.
Although OP asks for "verify data is copied quickly", Google pointed me here to "verify a multi-AZ RDS deploy". I'll share what I found in hopes that it's halfway helpful.
In the RDS console, there is an option on reboot to Reboot from failover which doesn't appear on a standard deploy.
Standard deploys do not have this option, which was a small but satisfying indication that the multi-AZ was acting as expected.
Source (and generally a pretty good read)
Q: Can I initiate a “forced failover” for my Multi-AZ DB instance
deployment?
Amazon RDS will automatically fail over without user intervention
under a variety of failure conditions. In addition, Amazon RDS
provides an option to initiate a failover when rebooting your
instance. You can access this feature via the AWS Management Console
or when using the RebootDBInstance API call.
Related
We need to know what are the best options to set AWS RDS instance (Aurora mysql) that is standalone and does not get traffic from actual RDS cluster.
Requirement is for our data team to write analytical queries but we do not want it to impact actual application and DB performance. Hence we need a DB which always has near to live data but live traffic or application does not connect to this instance.
Need to know which fits better, DL clone OR AWS Pilot light OR AWS Warn standby OR AWS hot standby OR
multi-AZ configuration.
Kindly let us know which one would fit our requirement better.
We have so far read about below 3 options,
AWS Amazon Aurora DB clone, https://docs.aws.amazon.com/AmazonRDS/latest/AuroraUserGuide/Aurora.Managing.Clone.html
AWS Pilot light or AWS Warn standby or AWS hot standby
. https://aws.amazon.com/blogs/architecture/disaster-recovery-dr-architecture-on-aws-part-iii-pilot- light-and-warm-standby/
With multi-AZ configuration, we can create a new instance in new AZ, so that his instance will have a different host (kind off, a fail over strategy), where traffic to his instance will be from our queries and not from live prod application, unless there is some fail over issue.
Option 1, Aurora cloning says
Run workload-intensive operations, such as exporting data or running analytical queries on the clone.
...which seems to be your use case here.
Just be aware that the clone will not see any changes to the original data after it is made. So you will need to periodically delete and re-clone to get the updated data
Regarding option 2, I wrote those blog posts, and I do not think that approach suits your use case. That approach is for disaster recovery
Option 3 may work. To modify it a bit, the concept here is to create an Aurora Replica, which as you say is a separate instance. The problem here is the reader endpoint for your production workload, it may hit that instance (which is not what you want)
EDIT: Adding new option 4
Option 4. Check out Amazon Aurora zero-ETL integration with Amazon Redshift. This zero-ETL integration also enables you to analyze data from multiple Aurora database clusters in an Amazon Redshift cluster.
I would like to setup a PostgreSQL database with read-only standby with automatic failover ability.
Does Amazon RDS with Multi-AZ have automatic failover ability?
If yes, will the endpoint/DNS automatically point to the new standby database?
There are 2 scenarios to this question as it was little ambiguous in the question.
scenario 1 :- rds with multi AZ.
Here standby instance will have automatic failover.
Here the endpoint/DNS automatically point to the new standby database, no manual intervention is needed.
But read and write is being taken by only the master DB and sync replication takes with standby database.
scenario 2 :- rds with multi AZ where read replicas is also there.
In this scenario read replicas are not treated like standby database database by default.howver they can be used like standby.
failover is not automatic.
You will need to manually update your dns.
article from aws says
A Read Replica in a different region than the source database can be used as a standby database and promoted to become the new production database in case of a regional disruption.
also a similar question on stack should also help you Difference between "Multi-AZ Deployment" and "Read Replica Verison Multi-AZ Deployment"
Scenario 2 seems to have slightly evolved since 2021.
Now this has become Multi-AZ DB Cluster
Reader DB instances act as automatic failover targets and also serve
read traffic to increase application read throughput. If an outage
occurs on your writer DB instance, RDS manages failover to one of the
reader DB instances. RDS does this based on which reader DB instance
has the most recent change record.
I want to autoscale AWS RDS automatically with scripts based on the metric monitoring.
RDS doesn't really do this for Read-Write
Multi AZ Write-Read database copies are intended for failover from primary to secondary if there is an availability problem. They don't address the problem of performance
Read replicas can be used to increase performance but they are read only
It might be possible to look at a load metric and use a Cloudwatch alarm to start an extra read replica. Read replicas can be used via an ELB or NLB
But probably this isn't a good idea. While an existing RDS is making a read replica, performance is degraded. RDS read replicas are quite slow to come up and become available so it's unlikely to respond in a good way to transient demand
You can make an API call to Modify an RDS Instance, including changing the instance class.
Amazon RDS will provision a new instance of the desired class and will then re-point the Endpoint to the new instance. Existing connections will be terminated, but applications can reconnect and all the data will be there.
Rather than scaling the RDS instance, you could always consider a caching layer, such as Amazon ElastiCache that supports Redis and Memcached. Most applications are read-heavy, which is ideal for using a cache. This can significantly improve application performance without having to scale the database.
In simple, it can be possible with Aurora 5.7 DB RDS instances only, they provide an option to auto-scale based on cloud watch metric conditions i.e CPU utilization etc.
I've been considering moving some databases from self-hosted database instances (e.g. MySQL or PostgreSQL on Linux, either bare-metal or within AWS itself) into Amazon RDS, but it's unclear to me how everything will behave once I've created the database and it's time for maintenance to begin.
For example, I have to choose the type of instance(s) that will be used for the database, which I guess means how responsive everything will be, and there is an option for multi-AZ deployments, but it's not clear how many of those types of instances I'm actually configuring. (Presumably, multi-AZ deployment requires at least two instances).
There are options for Failover, which leads me to believe that I can rely on the service to stay up if there are problems with an instance, but then there is also a section for selecting maintenance windows for automated upgrades, which I find confusing. If I were administering e.g. a two-instance MySQL setup, I'd upgrade one instance and then the other to avoid any downtime. Is that not how RDS behaves?
RDS advertises support for automatic "minor version upgrades" (yes, please), but doesn't say anything about OS upgrades. Presumably, the db engine will be running on Amazon Linux or something similar, and will periodically require updates to those packages. Does that all happen automatically, or do I need to manually perform those upgrades, etc.?
The whole point of using something like RDS is that the service should become something I no longer have to worry about: I don't have to deal with package maintenance, upgrades, failover, or unexpected downtime (as long as I pay enough, of course). But all of the options for the RDS instance are making me skeptical of the advantages provided by RDS over just running everything myself.
Can anyone with experience with AWS RDS comment on their experiences with maintenance, upgrades, and failover?
These were the same concerns which we had when we were planning to use RDS. Now that we are effectively using AWS RDS for multiple production workloads, let me try to clarify your queries. Hope this helps.
Your Question 1 : I have to choose the type of instance(s) that will be used for the database, which I guess means how responsive everything will be
Answer : Yes. This is to define what capacity (CPU,RAM etc) you will need for your database workload
Your Question 2 : There is an option for multi-AZ deployments, but it's not clear how many of those types of instances I'm actually configuring.
Answer : Multi-AZ deployments are to ensure high availability. AZ (Availability Zones) are isolated locations within an AWS Region to provide better protection against disaster scenarios. So when we choose a Multi AZ deployment, RDS will place 2 instances of your database server in 2 Availability Zones in the region where you are provisioning.
This is done automatically by RDS and we dont have to setup/maintain 2 servers separately/manually. ( Note : Your VPC should have atleast 1 subnet in each of the 2 different AZ to provision Multi AZ Setup)
Your Question 3: If I were administering e.g. a two-instance MySQL setup, I'd upgrade one instance and then the other to avoid any downtime. Is that not how RDS behaves?
Yes. RDS does it by itself without manual intervention if you enable Automatic Upgrades while setting up RDS (Only if you choose to have Multi AZ option)
Your Question 4 : RDS advertises support for automatic "minor version upgrades" (yes, please), but doesn't say anything about OS upgrades.
Answer : RDS dont expose/provide any OS access to us. The underlying OS and its upgrades/other activities are all done without affecting the RDS services hosted on top of it. We dont have to do anything about the OS of RDS. So we can forget about that part.
Your question 5 : Regarding Failover of AWS RDS Multi AZ database
I would classify into 2 cases.
Case 1 : Fail-overs required during maintenance/other automatic activities done by Multi AZ RDS instance.
Here, RDS will automatically do the failover one instance at a time. It will first move all the ongoing traffic to second instance and then upgrade/reboot the first instance and then do the same with second instance.
Case 2 : Fail-overs required during manual reboot/manually triggered actions done on Multi AZ RDS instance.
In this case, during the reboot, AWS RDS provides an option for you to select whether the reboot should be with failover or without one.
We have 4 standalone, non-multiAZ aurora DB instances in a VPC and we want to move them to aurora instances in another VPC.
As I understand there are 3 ways to migrate DB instances:
1) Modify the DB instance's Subnet group to change the VPC.
However this is not supported for Aurora instances yet.
2) Create a read replica, and when slave catches up, stop the slave and take it's snapshot to create a DB instance in the different VPC and use external slave then to again resume the replication.
I have a few question around this second method. As Aurora is using some different
replication method, the result of show slave status; command is empty.
Also by default the binlog_format is OFF so not sure if I have to modify it and
then restart the instance to take note of the binlog etc.
Have anyone done this before and can guide me? I don't want to restart the instance
to later find out that it is not working, as it is a very critical DB and I want to
minimize the downtime.
3) Use Amazon DMS service, however I cannot find the source DB details for Aurora in the documentation here.
I need to find out what all permissions to give to the replication user
I'll create for this. This command in aurora is not working,
GRANT REPLICATION CLIENT, REPLICATION SLAVE ON . TO 'replication_user'#'%'
IDENTIFIED BY 'aaaaaa';
Any help would be appreciated.
You should be able to restore from a snapshot. I migrated aurora across VPCs using this approach. I hoped we could create a read-replica in a different VPC but at the moment I think you can only create one in a different region.
One strange side effect I have found and i'm not sure why this happens is that in the orginal cluster multi-az was 2 Zones and in the restored cluster multi-az is No. This hasn't affected things that I can see. I still have a cluster with writer and reader
Create a snapshot and restore it to a new cluster. When you do that, use a new subnet group created for the second VPC. That's the best way to achieve this. Like you called out, you cannot change subnet group for an existing cluster.
In your approach #2, you mention having to create a slave and then taking a snapshot. That's not required. All instances in a cluster are connected to the same shared volume, so you can just go ahead and create a snapshot from your single instance cluster directly. Just make a note that snapshots are a cluster level action, and not an instance level action in Aurora.
From https://aws.amazon.com/premiumsupport/knowledge-center/rds-vpc-aurora-cluster/
It states that
Create a clone in a different VPC
If you clone a database in an Aurora cluster, you can change the VPC of the clone. > However, the subnets in the VPC must map to the same set of Availability Zones. For more information, see Cloning Databases in an Aurora DB Cluster.
It does work though can't see a way via the console to break the replication. We are using this as a faster way of migrating than snapshot and restore. Stopping the original master would break replication but though you could do it cleaner