Ok, thansk, that sounds good. In short, in each subnet, we need at least one R&R
node, and more than one to improve availability.
The answer to my other question is less clear: is it ok for R&R nodes to not
have knowledge of *all* other R&R nodes? For eg:
1. on subnet1, we bring up 5 peers and 1 R&R, which has
VIRTUAL_MULTICAST_URI_LIST populated with only itself
2. on subnet2, an R&R node is brought up with its URI list showing both itself
and the one on subnet1
3. 5 non-R&R peers come up on subnet2
Will the above work reliably? My testing shows that it works, but can I rely on
it working, since the docs explictly state that all R&R nodes must have the same
URI list?
Another thing that I just thought of, what happens if we reverse the order of 2
& 3 in my scenario? I'm guessing that two independent groups will be created,
and then merge into one. Will join events be fired when they merge?
-Jerry
Mohamed Abdelaziz wrote:
> You must at least designate a single node (or more for availability) as
> the seed node in such an environment, in order to overcome churn in the
> cluster. In addition, and depending on the cluster size, you may
> designate additional nodes to take on that role (10-1 ratio), as they
> are discovered, they will be used in the event the seed nodes seize to
> operate, or for load distribution.
>
> Mohamed
>
>
> On 7/10/09 3:13 AM, Jerry Raj wrote:
>> Hi Folks,
>> I've been able to get shoal working across subnets as described in
>> [1]. In that
>> document, it states that VIRTUAL_MULTICAST_URI_LIST should be the same
>> across
>> all peers. This may not be feasible, since the lifetime of the group
>> may be
>> quite long and peers may come and go across different subnets. Each
>> time a peer
>> shows up in a new subnet, it may be possible to discover (out-of-band)
>> the
>> existing R&R nodes, but the existing R&R nodes will not add this new
>> peer to
>> their VIRTUAL_MULTICAST_URI_LISTs.
>> In my testing, I could actually see that the above scenario actually
>> worked
>> fine, ie even when some R&R nodes do not know about all the other R&R
>> nodes. Can
>> I rely on this behavior?
>> In a related question, I could even see group membership and messaging
>> working
>> fine across subnets when VIRTUAL_MULTICAST_URI_LIST was not set for
>> non-R&R
>> nodes. Is this a defined behavior?
>>
>> -Jerry
>> [1]
>> http://wikis.sun.com/display/shoal/Shoal+How-To+-+Configuring+for+cross+subnet+support
>>
>>
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