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b4f2aa15b1
This is not true. You can run live databases on a glusterfs mount - if they access from ONE client. The documentation is misleading at this point. In the mailingslist you find a lot of users that use glusterfs for "live data".
116 lines
6.2 KiB
Markdown
116 lines
6.2 KiB
Markdown
# Overview
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### Purpose
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The Install Guide (IG) is aimed at providing the sequence of steps needed for
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setting up Gluster. It contains a reasonable degree of detail which helps an
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administrator to understand the terminology, the choices and how to configure
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the deployment to the storage needs of their application workload. The [Quick
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Start Guide](../Quick-Start-Guide/Quickstart.md) (QSG) is designed to get a
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deployment with default choices and is aimed at those who want to spend less
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time to get to a deployment.
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After you deploy Gluster by following these steps, we recommend that you read
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the [Gluster Admin Guide](../Administrator-Guide/index.md) to learn how to
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administer Gluster and how to select a volume type that fits your needs. Also,
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be sure to enlist the help of the Gluster community via the IRC or, Slack
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channels (see https://www.gluster.org/community/) or Q&A section.
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### Overview
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Before we begin, let’s talk about what Gluster is, address a few myths
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and misconceptions, and define a few terms. This will help you to avoid
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some of the common issues that others encounter as they start their journey with Gluster.
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#### What is Gluster
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Gluster is a distributed scale-out filesystem that allows rapid
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provisioning of additional storage based on your storage consumption
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needs. It incorporates automatic failover as a primary feature. All of
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this is accomplished without a centralized metadata server.
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#### What is Gluster without making me learn an extra glossary of terminology?
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- Gluster is an easy way to provision your own storage backend NAS
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using almost any hardware you choose.
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- You can add as much as you want to start with, and if you need more
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later, adding more takes just a few steps.
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- You can configure failover automatically, so that if a server goes
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down, you don’t lose access to the data. No manual steps are
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required for failover. When you fix the server that failed and bring
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it back online, you don’t have to do anything to get the data back
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except wait. In the meantime, the most current copy of your data
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keeps getting served from the node that was still running.
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- You can build a clustered filesystem in a matter of minutes… it is
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trivially easy for basic setups
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- It takes advantage of what we refer to as “commodity hardware”,
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which means, we run on just about any hardware you can think of,
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from that stack of decomm’s and gigabit switches in the corner no
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one can figure out what to do with (how many license servers do you
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really need, after all?), to that dream array you were speccing out
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online. Don’t worry, I won’t tell your boss.
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- It takes advantage of commodity software too. No need to mess with
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kernels or fine tune the OS to a tee. We run on top of most unix
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filesystems, with XFS and ext4 being the most popular choices. We do
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have some recommendations for more heavily utilized arrays, but
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these are simple to implement and you probably have some of these
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configured already anyway.
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- Gluster data can be accessed from just about anywhere – You can use
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traditional NFS, SMB/CIFS for Windows clients, or our own native
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GlusterFS (a few additional packages are needed on the client
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machines for this, but as you will see, they are quite small).
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- There are even more advanced features than this, but for now we will
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focus on the basics.
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- It’s not just a toy. Gluster is enterprise-ready, and commercial
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support is available if you need it. It is used in some of the most
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taxing environments like media serving, natural resource
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exploration, medical imaging, and even as a filesystem for Big Data.
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#### Is Gluster going to work for me and what I need it to do?
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Most likely, yes. People use Gluster for storage needs of a variety of application workloads. You are
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encouraged to ask around in our IRC or, Slack channels or Q&A forums to see if
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anyone has tried something similar. That being said, there are a few
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places where Gluster is going to need more consideration than others.
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- Accessing Gluster from SMB/CIFS is often going to be slow by most
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people’s standards. If you only moderate access by users, then it most
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likely won’t be an issue for you. On the other hand, adding enough
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Gluster servers into the mix, some people have seen better performance
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with us than other solutions due to the scale out nature of the
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technology
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- Gluster is traditionally better when using file sizes of at least 16KB
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(with a sweet spot around 128KB or so).
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#### What is the cost and complexity required to set up cluster?
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Question: How many billions of dollars is it going to cost to setup a cluster?
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Don’t I need redundant networking, super fast SSD’s,
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technology from Alpha Centauri delivered by men in black, etc…?
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I have never seen anyone spend even close to a billion, unless they got
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the rust proof coating on the servers. You don’t seem like the type that
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would get bamboozled like that, so have no fear. For the purpose of this
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tutorial, if your laptop can run two VM’s with 1GB of memory each, you
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can get started testing and the only thing you are going to pay for is
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coffee (assuming the coffee shop doesn’t make you pay them back for the
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electricity to power your laptop).
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If you want to test on bare metal, since Gluster is built with commodity
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hardware in mind, and because there is no centralized meta-data server,
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a very simple cluster can be deployed with two basic servers (2 CPU’s,
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4GB of RAM each, 1 Gigabit network). This is sufficient to have a nice
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file share or a place to put some nightly backups. Gluster is deployed
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successfully on all kinds of disks, from the lowliest 5200 RPM SATA to
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mightiest 1.21 gigawatt SSD’s. The more performance you need, the more
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consideration you will want to put into how much hardware to buy, but
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the great thing about Gluster is that you can start small, and add on as
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your needs grow.
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#### OK, but if I add servers on later, don’t they have to be exactly the same?
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In a perfect world, sure. Having the hardware be the same means less
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troubleshooting when the fires start popping up. But plenty of people
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deploy Gluster on mix and match hardware, and successfully.
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Get started by checking some [Common Criteria](./Common-criteria.md)
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