Open Stack

What happens if a ZoneManager process dies? When the ZoneManager restarts, the compute nodes will send their attributes to the newly restarted ZoneManager and the in-memory list of attributes will be reconstructed, right?
The only downside to this approach is the (probably short) time that it takes for the restarted ZoneManager to reconstruct its in-memory db of host attributes.

As an unrelated side note, the folks over in Hadoop land use this sort of 'in-memory data-structures fed by heartbeats' approach with much success.

- Jagane
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From: openstack-bounces+jagane=sundar.org at lists.launchpad.net [openstack-bounces+jagane=sundar.org at lists.launchpad.net] On Behalf Of Sandy Walsh [sandy.walsh at rackspace.com]
Sent: Friday, April 15, 2011 2:24 PM
To: Jay Pipes; Ed Leafe
Cc: Mark Washenberger; openstack at lists.launchpad.net
Subject: Re: [Openstack] distributed and heterogeneous schedulers

Each update from the services are atomic updates ... fully self contained.

Why does this need to be in a persistent store?

-S
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From: Jay Pipes [jaypipes at gmail.com]
>  you still need a persistent data store for attributes of the host. Just because you
> store a cached in-memory copy of instance attributes, doesn't mean you
> don't need a persistent data store. You still need a persistent data
> store regardless of whether it's a database table, a FLAG value, or
> /proc/cpuinfo.

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