openstack team mailing list archive

[Jagane Sundar <jagane@xxxxxxxxxx>]

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
________________________________________
From: openstack-bounces+jagane=sundar.org@xxxxxxxxxxxxxxxxxxx [openstack-bounces+jagane=sundar.org@xxxxxxxxxxxxxxxxxxx] On Behalf Of Sandy Walsh [sandy.walsh@xxxxxxxxxxxxx]
Sent: Friday, April 15, 2011 2:24 PM
To: Jay Pipes; Ed Leafe
Cc: Mark Washenberger; openstack@xxxxxxxxxxxxxxxxxxx
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@xxxxxxxxx]
>  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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