I had cluster with two master nodes in replica set. I call vshard.router.callrw api, but request sent always only to first (leader) master. How should I send request to all masters with load balancing?
Current vshard version doesn't support multimater configuration (https://github.com/tarantool/vshard/issues/165). But you could use "callro" for such purposes.
Related
I have installed Postgres cluster using zalando operator.
Also enabled pgbouncer for replicas and master.
But I would like to combine or load balance replicase and master connections,
So that read requests can be routed to read replicas and write requests can be routed to master.
Can anyone help me out in achieving this.
Thanks in advance.
Tried enabling pgbouncer.
pgbouncer is getting enabled either to master or to slave.
But I need a single point where it can route read requests to slaves and write requests to master.
There is no safe way to distinguish reading and writing statements in PostgreSQL. pgPool tries to do that, but I think any such solution is flaky. You will have to teach your application to direct reads and writes to different data sources.
I don't think Pgbouncer provides any out of the box way to load balance read and write queries. An alternative to that is the use of pgpool as a connection pooler. Pgpool provides a mode known as load_balance_mode which you can turn it on and it will try to load balance queries and send write queries to master and read queries to replica. You can read more about the load_balance_mode here
Can Apache Mesos 'slave' nodes be located on a separate network than the Mesos 'master' nodes? Similarly (for high-availability (HA) deploys), can the Apache Zookeeper nodes used in Mesos 'master' election be deployed on a separate network than the Mesos 'slave' nodes?
Currently, I have 3 masters+slaves nodes in the cloud, and I want to add a slave installed in my local subnet.
If such a setup is feasible, what are the pros/cons of such a setup?
I think https://www.stratio.com/blog/mesos-multi-data-center-architecture-for-disaster-recovery/ is a nice read on several of the things you need to make this work. There are some scenarios on how to handle stuff if a DC is down.
Pros:
You can failover in case of a DC being down/unreachable
Cons:
Both DC's must be able to run the environment by itself (active, or you should be able to scale up fast), so that creates overhead costs
Complexity increases (network, mesos/application configuration)
About the networks: they must be able to connect somehow, so public (but encrypted and firewalled, I also think that every node needs a public IP) or via an ipsec tunnel or another option like the link mentions.
I don't think doing it via the internet without tunneling (so the first option I mention) is a very good option.
I've read all the docs on the Google Cloud SQL site, and I now understand how to created and manage Read Replicas, but I have not seen any information about how to use them,
Does Google automatically load-balance connections between all instances?
Do I have to manually connect to a specific Read Replica to avoid hitting the Master? If so, do I have to manage reconnecting on replica failure myself?
Does Google automatically load-balance connections between all instances?
No, it doesn't. Each instance is independent. You can connect to replicas and use them to read while using the master to read/write, but you need to design that logic into your application
Do I have to manually connect to a specific Read Replica to avoid hitting the Master? If so, do I have to manage reconnecting on replica failure myself?
Yes, you have to connect to a specific read replica. Right now you can't even save and reuse the instance IP like you can do with compute engine instances (sigh, I hope they fix this soon....).
There is now a failover replica option that you can use so you don't need to connect to the read replica yourself, but it only activates on failure, it is not a load balancer.
Read replica can be used by setting up ProxySQL. You can configure ProxySQL to distribute the database queries. Here is a community tutorial providing more details on architecture and configuration example.
How do I use Read Replicas?
Use them for disaster recovery or to migrate your database to
another region by promoting a read replica to become a primary
database.
https://cloud.google.com/sql/docs/postgres/replication/cross-region-replicas
Use them for separating read workloads from production workloads. This blog post covers using Read Replicas for analytics workloads:
Use Cloud SQL Read Replicas to separate your analytics and production workloads
Cloud SQL does not provide load balancing between replicas1
ref:https://cloud.google.com/sql/docs/sqlserver/replication
I have three server A,B,C on each machine I'm running Chronos, ZooKeeper, mesos-master, mesos-slave.
Chronos contact mesos-master using ZooKeeper url hence it automatically picks leading master even if some node is down. I'm having high availability here.
Even Chronos run in cluster mode so accessing any of the Chronos I see same list of jobs and everything works fine.
Problem I have here is, Chronos is accessible with any of the three URLs
http://server_node_1:4400
http://server_node_2:4400
http://server_node_3:4400
I have another application which schedules jobs in Chronos using Rest API. Which URL my application has to talk to in order in run in high availabiity mode?
Let's say my application talks to http://server_node_1:4400 for scheduling the job, if Chronos on node server_node_1 is down I'm not able to schedule the Job.
My application needs to talk to single URL in order to schedule job in Chronos. Even if some Chronos node is down, I should be able to schedule the job. Do I need to have some kind of load balancer between my application and Chronos cluster to pick running chronos node for job scheduling? How can I achieve high availability in my scenario?
Use HAProxy for routing to a Chronos instance. This way you can access a Chronos instance using e.g. curl loadbalancer:8081.
haproxy.cfg:
listen chronos_8081
bind 0.0.0.0:8081
mode http
balance roundrobin
option allbackups
option http-no-delay
server chronos01 server_node_1:4400
server chronos02 server_node_2:4400
server chronos03 server_node_3:4400
Or even better, start Chronos via Marathon, which will ensure given number of instances. Then HAProxy configuration could be generated by:
marathon-lb
bamboo
I am trying to setup a very simple cluster of 2 ejabberd nodes. However, while trying to go through the official ejabberd documentation and using the join_cluster argument that comes along with the ejabberdctl script, I always end up with a multi-master cluster where both the mnesia databases have replicated data.
Is it possible to set up a ejabberd cluster in master-slave mode? And if yes, then what I am I missing?
In my understanding, a slave get the data replicated but would simply not be active. The slave needs the data to be able to take over the task of the master at some point.
It seems to means that the core of the setup you describe is not about disabling replication but about not sending traffic to the slave, no ?
In that case, this is just a matter of configuring your load balancing mechanism to route the traffic accordingly to your preference..