Reliable Cloud host ?

Jon Lewis jlewis at lewis.org
Sun Feb 26 18:29:40 CST 2012


On Sun, 26 Feb 2012, Randy Carpenter wrote:

> This does not have to be true at all.  Even having a fully 
> fault-tolerant SAN in addition to spare servers should not cost much 
> more than having separate RAID arrays inside each of the server, when 
> you are talking about 1,000s of server (which Rackspace certainly has)

When is your cloud offering going to be available to the public?

> I don't need that kind of HA, and understand that it is not going to be 
> available. 15 minutes of downtime is fine. 6 hours is completely 
> unacceptable, and it false advertising to say you have a "Cloud" 
> service, and then have the realization that you could have *indefinite* 
> downtime.

I think you're assuming "cloud" means things that the provider does not. 
To me, "cloud" just means VPS that I can create/destroy quickly whenever I 
feel like it, without any interaction from the provider's people.  i.e. a 
few mouse clicks or an API call can "provision a 10gb CentOS VM with 256mb 
RAM".  It's up and running before I could locate a CentOS install CD, and 
if I don't like it, a few clicks or an API call deletes it, reprovisions 
it, exchanges it for a Ubuntu server, etc.  Cloud doesn't mean if the node 
my VM(s) are on dies or crashes, my VMs boot up on an alternate node. 
That would certainly be a nice feature, but that's just a form of 
redundancy in a cloud...not a defining attribute of cloud.

> The funky problem with DNS specifically, is that all the servers need to 
> be up, or someone will get bad answers. Not having a preference system,

DNS "handles" down servers.  How would one of your DNS servers being down 
give someone bad answers?  It won't give any answers, and another server 
will be queried.  Or do you mean if storage "goes away", but your DNS 
server is still running, it'll either give nxdomain or stale 
data...depending on whether it had the data in memory or storage went away 
and updates began failing because of it?

----------------------------------------------------------------------
  Jon Lewis, MCP :)           |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                |
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