My knowledge of Windows Azure is limited to the several videos I watched on Microsoft's web site. Aside from a few new buzzwords, I'm not seeing how this platform differentiates from traditional web hosts that have existed for many years. Aside from the unique billing model (e.g. "storage transactions per month"), what differentiates Azure from traditional web hosts, such as discountasp.net, in terms of the actual service provided?
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A:
The extra services that takes cloud computing(Azure) one step beyond traditional hosting? Here are a few:
Load balancing: a flexible set of computing resources can all be transparently load-balanced behind a virtual router.
Content Delivery: the work done by a content delivery network can all be done transparently by a cloud computing provider, such as Amazon CloudFront.
Failover: if your data is load-balanced between multiple data centers, and one data center goes offline, a cloud computing provider should be able to failover the traffic from one to the others. (If they can't now, they should provide this service. :))
Scalability: the number of compute resources used should automatically scale up or down based on demand.
Tooling: with the advent of mainstream cloud computing providers, the tooling has improved tremendously. For example, Windows Azure tools allow developers to test everything out locally and easily deploy to the cloud, and thus enabling people to easily build scalable services.
Sachin Shanbhag
2010-10-21 13:30:23
All good general points, but to talk about Azure specifically, all of the good things only come into effect if you have more than 1 instance running. It does have automatic fail over, but only within the data centre. A meteor could still take out your data unless you have rolled your own off site backup. It is very easy to increase the number of instances you have to deal with increased load, but it is not automatic. If you want this, currently you need to roll your own.
knightpfhor
2010-10-21 19:45:37
@knightpfhor - that's not necessarily true. You still have scalability, content delivery, failover, and tooling as mentioned above, even with a single instance. The 99.95% availability SLA is dependent on multiple instances, which are then hosted in separate fault domains so that, if a single rack fails, you will still have a running VM on another rack.
David Makogon
2010-10-22 00:02:54
The important thing to note there is that it's on another rack, not another data centre which is what is stated in this answer. If you have just a single instance you don't have failover, that whole instance is unavailable until it can be either restarted or reprovisioned.
knightpfhor
2010-10-22 01:47:41
A:
As Sachin pointed out, there are several core concepts to Azure that benefit you beyond something such as DiscountAsp. I'd like to point out a few more Azure-specific nuances. These benefits typically apply whether you have one instance or multiple - it's just that you might experience a slight bit of downtime if certain events cause a redeploy of your app.
- Health monitoring. Unlike DiscountASP or any discount web host, the Azure fabric keeps tabs on the health of your virtual machines, and deals with restarts or machine moves as necessary.
- OS maintenance. The Azure Guest OS images are updated frequently (I've seen a rough average of 1 month between updates). This includes security patches such as the ASP.NET vulnerability, as well as other OS updates.
- Durable storage. With tables, blobs, and queues, along with SQL Azure, data is triple-replicated, so there's no risk of data loss (unless you explicitly delete data, and then you've triple-replicated your delete).
- On-demand provisioning. SQL Azure, for instance, deploys a new database in a matter of seconds. For virtual machine instances, this takes about 15-20 minutes to deploy (e.g. you want to scale up your app from 2 to 4 servers).
- Service bus. With AppFabric service bus, you can connect to on-premise resources without opening up your firewall.
- Access control. Azure provides hooks into several providers such as Live ID and Yahoo!
- Consumption-based services. Everything I've listed is a la carte; you pay for what you use. There's no specific monthly commitment for a given set of servers, for instance. With other hosters where you pay by the box, for instance, you have a fixed cost per month.
- Dedicated virtual machines. While it's true that Azure runs multiple virtual machines on a single box, each box is limited to 8 cores, which equates to either 1, 2, 4, or 8 VMs running on that server. With DiscountASP and other discount hosters, there may be dozens or hundreds of web sites hosted on the same box, and your performance will vary depending on those web sites' activities, RAM usage, and CPU usage.
There are probably a few more benefits of Azure over discount web hosting, but that should give you a good start.
David Makogon
2010-10-22 00:00:43