In case you guys are curious. Jclouds supports the new cluster instances and 
placement groups. We should talk about how whirr can use this info.  

Adrian

-------- Original Message --------
Subject: RE: placement groups
From: "Lipscomb, Trenton" <[email protected]>
To: Adrian Cole <[email protected]>
CC: null

Sorry I missed a follow up on this. I haven't written up my trip report, and 
your question was buried in there. Apologies.

I asked the principal engineer on HPC and here was his repose. We've also asked 
the PMs (who write the docs) to improve the explanations.


Clustered placement groups are relegated to a single AZ, and that will be true 
forever. You can currently start more than one placement group in a single AZ, 
and we expect that to be common. Each group will independently experience the 
"clustering" benefits within the group, but not necessarily between groups even 
in the same AZ.



As the placement group API evolves, it's possible that future strategies will 
straddle multiple AZs or even regions.

Let me know if you need anything else.

I hope, too, using the boot device flag helped you to keep track of which 
volumes go with which hosts.

*trenton


From: Adrian Cole [mailto:[email protected]]
Sent: Friday, July 30, 2010 1:09 PM
To: Lipscomb, Trenton
Subject: placement groups

Hi, Trenton,

Thanks for chatting with me at length during oscon.  Let me know, if you've 
found anything out about those new placement groups for the cluster instances.  
I'm working with cloudera and would like to understand the scope and usage 
correctly.

Cheers,
Adrian
jclouds & opscode

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