The Install Guide (IG) is aimed at providing the sequence of steps needed for setting up Gluster. It contains a reasonable degree of detail which helps an administrator to understand the terminology, the choices and how to configure the deployment to the storage needs of their application workload. The Quick Start Guide (QSG) is designed to get a deployment with default choices and is aimed at those who want to spend less time to get to a deployment.
After you deploy Gluster by following these steps, we recommend that you read the Gluster Admin Guide (AG) to learn how to administer Gluster and how to select a volume type that fits your needs. Also, be sure to enlist the help of the Gluster community via the IRC or, Slack channels (see https://www.gluster.org/community/) or Q&A section.
Before we begin, let’s talk about what Gluster is, address a few myths and misconceptions, and define a few terms. This will help you to avoid some of the common issues that others encounter as they start their journey with Gluster.
What is Gluster
Gluster is a distributed scale-out filesystem that allows rapid provisioning of additional storage based on your storage consumption needs. It incorporates automatic failover as a primary feature. All of this is accomplished without a centralized metadata server.
What is Gluster without making me learn an extra glossary of terminology?
- Gluster is an easy way to provision your own storage backend NAS using almost any hardware you choose.
- You can add as much as you want to start with, and if you need more later, adding more takes just a few steps.
- You can configure failover automatically, so that if a server goes down, you don’t lose access to the data. No manual steps are required for failover. When you fix the server that failed and bring it back online, you don’t have to do anything to get the data back except wait. In the meantime, the most current copy of your data keeps getting served from the node that was still running.
- You can build a clustered filesystem in a matter of minutes… it is trivially easy for basic setups
- It takes advantage of what we refer to as “commodity hardware”, which means, we run on just about any hardware you can think of, from that stack of decomm’s and gigabit switches in the corner no one can figure out what to do with (how many license servers do you really need, after all?), to that dream array you were speccing out online. Don’t worry, I won’t tell your boss.
- It takes advantage of commodity software too. No need to mess with kernels or fine tune the OS to a tee. We run on top of most unix filesystems, with XFS and ext4 being the most popular choices. We do have some recommendations for more heavily utilized arrays, but these are simple to implement and you probably have some of these configured already anyway.
- Gluster data can be accessed from just about anywhere – You can use traditional NFS, SMB/CIFS for Windows clients, or our own native GlusterFS (a few additional packages are needed on the client machines for this, but as you will see, they are quite small).
- There are even more advanced features than this, but for now we will focus on the basics.
- It’s not just a toy. Gluster is enterprise-ready, and commercial support is available if you need it. It is used in some of the most taxing environments like media serving, natural resource exploration, medical imaging, and even as a filesystem for Big Data.
Is Gluster going to work for me and what I need it to do?
Most likely, yes. People use Gluster for storage needs of a variety of application workloads. You are encouraged to ask around in our IRC or, Slack channels or Q&A forums to see if anyone has tried something similar. That being said, there are a few places where Gluster is going to need more consideration than others.
- Accessing Gluster from SMB/CIFS is often going to be slow by most people’s standards. If you only moderate access by users, then it most likely won’t be an issue for you. On the other hand, adding enough Gluster servers into the mix, some people have seen better performance with us than other solutions due to the scale out nature of the technology
- Gluster does not support so called “structured data”, meaning live, SQL databases. Of course, using Gluster to backup and restore the database would be fine
- Gluster is traditionally better when using file sizes of at least 16KB (with a sweet spot around 128KB or so).
What is the cost and complexity required to set up cluster?
Question: How many billions of dollars is it going to cost to setup a cluster? Don’t I need redundant networking, super fast SSD’s, technology from Alpha Centauri delivered by men in black, etc…?
I have never seen anyone spend even close to a billion, unless they got the rust proof coating on the servers. You don’t seem like the type that would get bamboozled like that, so have no fear. For the purpose of this tutorial, if your laptop can run two VM’s with 1GB of memory each, you can get started testing and the only thing you are going to pay for is coffee (assuming the coffee shop doesn’t make you pay them back for the electricity to power your laptop).
If you want to test on bare metal, since Gluster is built with commodity hardware in mind, and because there is no centralized meta-data server, a very simple cluster can be deployed with two basic servers (2 CPU’s, 4GB of RAM each, 1 Gigabit network). This is sufficient to have a nice file share or a place to put some nightly backups. Gluster is deployed successfully on all kinds of disks, from the lowliest 5200 RPM SATA to mightiest 1.21 gigawatt SSD’s. The more performance you need, the more consideration you will want to put into how much hardware to buy, but the great thing about Gluster is that you can start small, and add on as your needs grow.
OK, but if I add servers on later, don’t they have to be exactly the same?
In a perfect world, sure. Having the hardware be the same means less troubleshooting when the fires start popping up. But plenty of people deploy Gluster on mix and match hardware, and successfully.
Get started by checking some Common Criteria