I started to implement bigchainDB.I have followed the tutorial from here
I have setup two nodes running bighchainDB server running & also mongoDB. I have added node id and address of nodes to each configuration so that they can connect.I am able to create transactions on each node.So my questions are as follow
How two nodes communicate and sync data with each other.
How consensus is achieved ?
Why this tutorial is created for setting up cluster ?
BigchainDB nodes communicate with each other using Tendermint P2P protocol. Consensus is Tendermint consensus. To understand those better, here are some starting points:
The BigchainDB 2.0 Whitepaper
The Tendermint website and docs
Also, please ignore the old docs for versions of BigchainDB Server older than 2.0.0x.
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CONTEXT: I have been learning Kubernetes and trying to get some hands-on experience. I have been using AKS to abstract the complexity of having to deal with the control plane (and because I have a free student azure account). I am deploying a NodeJS app that connects to the MongoDB database. So far the deployment has been successful but I am using MongoDB Atlas and connecting to it.
Based on the little I have learned about Stateful sets, the MongoDB Atlas service seems a lot easier and more convenient but my question is, when would it be a better idea to consider deploying a stateful set with MongoDB database? (running on the pod) What's more cost-effective? More easily scalable?
I realize the questions might be a little bit vague but I am just getting started with Kubernetes..
disclaimer: This is not a production application, just something simple I am using to learn K8S
Official docs docs uses statefullset and that would make sense. Generally all DB kind of applications deployed as statefullset. Because there can be states that nodes are not sync with each other and that would create data inconsistencies between nodes(mongodb nodes not kubernetes).
You can deploy MongoDB as deployment. I have seen it deployed. But most clients use a connection string to connect(a string of multiple node addresses). And since kubernetes exposes statefullsets with headless services you should be okay.
For learning purpose, I advice you to deploy your MongoDB in a StatefulSet. Then you can learn how it works and what problem you could encounter with this Kubernetes object.
For production application, I advice to never deploy a database in a StatefulSet if you don't need it. In fact, StatefulSet will come with a lot of problematics that you might not need to manage.
Sometimes, companies rules restrict to host their data on external company storage.
To know if you need to put your database in a StatefulSet, the question I try to answer is:
Should my DB be hosted on premise (for privacy)?
Should my DB be scalable?
Should my DB be updated frequently?
You can find a list of pros/cons on the documentation.
I'm fairly new to MongoDB (Atlas - free tier), where I have created a project using it for storing my data. I had it set up and working fine for a couple of weeks, when suddenly I received an email with: An alert is open for your Atlas project: Replica set has no primary. I have no idea what this means and I don't believe I have done anything in the last couple of days/weeks that could warrant this alert. However, after checking my project, it seems that I can no longer connect to my cluster and access my data.
After checking on MongoDB Cloud, it seems that my cluster has stopped working and only the secondary shard (don't know if this is the right terminology) is running, while the other two seem to be down. Can anyone explain what this means, why it is happening or how to fix it? Thanks.
To troubleshoot issues like this, read the server logs and act based on the information therein.
For free and shared tiers in Atlas the logs are apparently not available. Therefore:
For a free tier cluster (M0), delete this cluster and create a new one. If you don't have a backup you should be able to dump via a direct connection to any of the operational secondary nodes or using the secondary read preference.
For a shared tier cluster (M2/M5), use the official MongoDB support channels for assistance.
I am a noob in Solr and zookeeper and trying to learn by myself. I understood that zookeeper is a file structure that manages solr cluster and prevents race condition using locks. I didn’t understand what is upconfig and downconfig and when we do that. It would be of great help if someone can give me a clear picture on it. Thanks in advance!
A better and more general description of Zookeeper is an application that provides centralised configuration for distributed systems. So in Solr Cloud, you can have multiple Solr instances across multiple servers acting together as a single cloud. However, if you want to update a collection's configuration, you don't want to have to go to each server and update them all individually. You want only one version of the config which is then used by any collection that needs it. Hence the conf commands.
upconfig uploads a configuration to ZooKeeper, which then ensures that all collections using that configuration (throughout the Cloud, on all the servers) have that specific config. So you only need to upload it once, on one server.
downconfig lets you fetch a configuration from Zookeeper.
I'm new to Akka Clusters, however as I am understanding its documentation, I need to know at least one "seed node" to join an existing cluster.
So when using clusters with OpenShift I would need to know if the current gear is the first node - then I would create a new cluster - or if there are already some other gears around - I would need to know at least one of their IPs to join them.
Is this possible with OpenShift cloud? (I'm using the DIY catridge, so customizing the start up script wouldn't be a problem. However I can't find any environment variable which provides me relevant data.)
DIY gears on OpenShift Online do not scale. And if you are spinning up separate applications for each of the nodes in your cluster, you are going to (probably) run into inter-gear communication issues. You might need to create your own akka cartridge (http://docs.openshift.org/origin-m4/oo_cartridge_developers_guide.html), then you can set your own scaling options. You might check out this cartridge (https://github.com/smarterclayton/openshift-redis-cart) which supports scaling and might give you some ideas about how to implement yours.
Is it possible to run more than one instance of MongoDB in Azure? I need (in the future) partition database to many node.
You can run multiple instances if you use a replica set, as you can then use internal endpoints for inter-node communication. If you only have standalone instances, they won't be able to communicate with each other and won't share data.
I've been presenting this at various Mongodb conferences (DC, Silicon Valley), and you can watch the Silicon Valley video recording of my presentation here.
EDIT: 10gen has now published a .NET project that launches a replicaset, improving upon the original work I did, and may be downloaded here, with docs here.