We need to change our hosting provider and we are evaluating various solutions.

My company has a cluster of 8 linux servers, configured as follow:

  • 2 load balancer (high availability)
  • 2 web server (load balancing)
  • 2 database MySql (replication)
  • 2 nfs server (high availability + drbd)

We manage about 200 web sites, some of them have an high traffic volume (20000 visitors per day). All our sites use a CMS developed by my company (so we need to be free to install all programs we want).

Is it a good idea to implement this cluster with a cloud virtual server? Which are the pros and cons?

Or is better to use a different solution? Other companies with similar need which kind of solutions they use?

I've heard about ibrid servers real/cloud, how is it possible to integrate them?

Anyone knows some providers that fit our needs?

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  • If you ask yourself this question then stay with whatever you currently have as there's no need for anything else. – pfo Sep 2 '11 at 14:50

The financials for figuring out if it is better (a.k.a. cheaper) to go cloud is an easier thing to figure out than figuring out if it is better for you (a.k.a. easier).

Cloud providers charge for usage in ways that you don't take into account when you own your entire infrastructure. Such charges may include any or all of the following:

  • Hours of run-time per server instance, per instance type (744/hours per month for 24/7 servers)
    • Extra cost for added CPU/RAM options for instance types
  • Use of specialist cloud infrastructure
    • Some offer network loadbalancers as a discrete service
    • Some offer simple file-storage as a discrete service
  • Network transfer between the cloud and the Internet
  • Network transfer between server instances within the cloud
  • Storage transfer between server instances and storage

This can make estimating your monthly costs quite hard if you don't know how much data you transact with your storage. For 24/7/365 always-on instances, cloud may very well not be a better deal than using with real servers.

The areas where Cloud can make your life easier (there is usually a cost for easy):

  • Deploying new servers is very, very simple.
  • Adding capacity on existing servers is as easy as paying for the option and rebooting.
  • Disposing of servers is as simple as deleting them, no futzing about with resale/recycle/disposal.

In general, and you'll have to do the math yourself to see if this fits your use case, if your infrastructure is static and not likely to change much over the course of 12 months, cloud is probably not a good fit. If you need the capacity to add a bunch of resources right now rather than in three weeks, cloud is a better fit.

It depends.

  • I would add a little "cons" against the Cloud services...you actually loose "ownership" and "control" of your data. I put them in quotations because legally you still own the data and control it...but you now entirely trust someone else with it. – Alex Sep 2 '11 at 15:39
  • Thank you for the answer. My main concern is about the migration to the cloud. How many instance of cloud servers I need to implement the same services. One instance is enough? As you can see, I have many doubts about it. – Alessandro Astarita Sep 2 '11 at 15:41
  • @AlessandroAstarita Unfortunately, the only way to figure that out is to do some trial migrations to see how well it works. It's like buying new servers, you won't know exactly how well they'll work until you try them out. – sysadmin1138 Sep 2 '11 at 15:52
  • Assuming that our cluster and one instance of a cloud server perform the same. Are rackspace or amazon cloud server, high available? – Alessandro Astarita Sep 2 '11 at 17:01
  • @AlessandroAstarita High availability is what you make of it. Amazon says in their terms of service that they're "best effort". If that's good enough for you, then that's HA. If you think you can do better, then don't go AWS. – sysadmin1138 Sep 2 '11 at 17:35

Pros to the cloud

  • You can quickly easily size the infrastructure to the demand as the demand changes. Getting smaller just as easy as getting larger.
  • You don't own infrastructure, and management of it is less involved.
  • The infrastructure is much less vulnerable to disaster or other outages.
  • Expenses are in a "flow" rather than in big chunks.
  • You get to visit really cool data centers!

Cons to the cloud

  • You already have a bunch of money invested in the existing infrastructure.
  • It is more expensive on a monthly basis, and the cost is somewhat out of your control.
  • Transitioning will be difficult, and doesn't really add value.
  • You become more dependent on third parties.

My advice .. I would not make such a change for it's own sake. Wait until circumstances are driving you to change. By that I mean something like outgrowing your current infrastructure, the existing hardware becoming unreliable, a need to move your building, or the deployment of a new version of your CMS.

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