Dan,
AFAIK, AZ gives you infrastructure redundancy but not necessarily
geographical dispersion. Regions are meant for that (as well as other
characteristics).
An interesting blog on this topic
http://alestic.com/2009/07/ec2-availability-zones
Cheers
<k/>
On 4/4/10 Sun Apr 4, 10, "Dan Di Spaltro" <dan.dispal...@gmail.com> wrote:
> A little off-topic, but is an availability zone in a separate physical
> datacenter?
>
> On Sat, Apr 3, 2010 at 5:08 PM, Benjamin Black <b...@b3k.us> wrote:
>> Right, you determine AZ by looking at the metadata. us-east-1a is a
>> different AZ from us-east-1b. You can't infer anything beyond that,
>> either with the AWS API or guesses about IP addressing. My EC2 snitch
>> recipe builds a config file for the property snitch that treats AZs
>> like racks (just breaking apart the AZ name, nothing magical), and the
>> rest is the normal rack aware placement strategy. I am sure folks
>> _could_ do interesting things on EC2 with extra code, but I don't see
>> extra code as required for these basic features.
>>
>>
>> b
>>
>> On Sat, Apr 3, 2010 at 3:04 PM, Joe Stump <j...@joestump.net> wrote:
>>>
>>> On Apr 3, 2010, at 2:54 PM, Benjamin Black wrote:
>>>
>>>> I'm pretty familiar with EC2, hence the question. I don't believe any
>>>> patches are required to do these things. Regardless, as I noted in
>>>> that ticket, you definitely do NOT need AWS credentials to determine
>>>> your availability zone. It is available through the metadata web
>>>> server for each instance as 'placement_availability_zone', avoiding
>>>> the need to speak the EC2 API or store credentials in the configs.
>>>
>>> Good point on the metadata web server. Though I'm unsure how Cassandra would
>>> know anything about those AZ's without using code that's aware of such
>>> things, such as the rack-aware strategy we made.
>>>
>>> Am I missing something further? I asked a friend on the EC2 networking team
>>> if you could determine AZ by IP address and he said, "No."
>>>
>>> --Joe
>>>
>>>
>>
>
>
