Posts Tagged ‘high-availability’

Cloud Computing Storage Options

Wednesday, June 22nd, 2011

One of the things that I find most interesting about cloud computing storage is “local storage” versus “centralized storage”. For a quick primer, local storage means the physical hard drives that reside in the servers that are used to run your instances in our cloud. Centralized storage would mean separate storage arrays that store your instances which are separate from the cloud servers. Since the option exists to select one or the other, let’s go ahead and break down the pros and cons for each one.

Local Storage:
If you select the local storage option, that simply means that your instances are running and being physically stored on the same servers. The upside to this is that your disk I/O speeds will typically be a bit quicker because everything is connected to the same bus on that server. This is really good if you’re running large database applications or have requirements for very fast disk reads and writes. The downside to this is that you give up the high availability options that are typically native to cloud computing. In other words, if that particular server goes down, your websites go down with it and they won’t be automatically migrated over to a different machine as that process has to be done manually because you’re not utilizing centralized storage. With local storage you are still able to make snapshots and restore from the snapshots to another available server, but it’s a manual process and does require human intervention. So even if you select local storage you still have the peace of mind of being able to automate snapshots and for those to be stored off of the server. Of course for a recovery, those snapshots have to be converted to a template and then the new instance would have to be spun up from those templates, but you will be back up and running again quickly. Again it requires manual intervention and while it takes less time than recovering from a typical dedicated server, it still takes a little time.

Centralized Storage:
If you select the centralized storage option, that means new instances are running on a local server but your actual instances are being stored on a separate storage device. So essentially the server that your instances are running on is being utilized solely for CPU and memory while all of the storage requirements are handled by a separate device which is attached to the network. The upside of this is the high-availability options which will just automatically work if the server that happens to be running your instances goes down. If that did happen, one of our management consoles would detect the failed server and will immediately scan the network for other available servers and instruct the server with the greatest amount of free resources to mosey over to the storage device and spin up those instances right away. This is much different than having to do a restore because there really is nothing to restore because your data is all still intact on the storage device. Free servers will spring into action, snatch up your instances and provide CPU and memory to them so they can spin up again and resume as normal. This entire high-availability recovery option typically gets completed in under a minute. So to recap, if the server that your instances are running on fails, others servers will take over operations within a minute without any intervention from human at all.

Hybrid Hosting:
Another option that is very viable and widely used is a hybrid approach which combines cloud computing and a dedicated server or managed server. If you have for example, (4) websites and you have (1) database that requires faster disk access, you can run your websites on the cloud using centralized storage for the (HA) high availability and only run your database on an instance that utilizes local storage for the speed. That way you get the best of both worlds, over-the-top high-availability for your websites and ultra fast storage for your database.

So as you can see there are plenty of options and it’s relatively simple to mix and match to find a solution that best suits your needs. We are always happy and eager to help come up with solutions for our clients, so let us know what we can do to help you.

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Do I need a dedicated database server?

Wednesday, June 17th, 2009

Well not always, but typically, yes. If you just want to sort your wedding or vacation pictures for family viewing, then probably not. Otherwise, three very good reasons why you should consider it are Security, Performance, Scalability. (more…)

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