---+ Installation on additional hosts

To add additional hosts to the Apache Tashi cluster, they should be 
installed to satisfy the prerequisites as described in the main 
installation document. However, only the node manager will have to be 
launched on these hosts. There should be only one cluster manager and 
scheduling agent in the cluster.

You must register the host's hostname with the clustermanager, as shown 
in the main installation document.

You can then start the node manager manually, or have it start from the 
system initialization scripts.

---+ VM host best practices

The nodemanager will use a small amount of local storage to keep 
accounting data on the virtual machines that it manages. The 
copy-on-write storage used by running virtual machines will also be 
written locally. For the sake of stability, these two storage locations 
should be chosen so that there is always sufficient space for the 
accounting data. Otherwise, this could lead to VMs running but not known 
to the nodemanager.

If you are using Qemu/KVM as the hypervisor, be advised that the VM 
format changes rather quickly. E.g. version 1.1 of Qemu states it will 
accept migrations in from versions 0.13 to 1.1. Migrations out are 
liable to be dropped on the floor by a receiving older version Qemu 
(with a successful return from the sending Qemu). Be careful to only 
deploy Qemu versions in your cluster that can work together. Since 
suspend and resume are handled via the same mechanisms, the above caveat 
applies to these actions too.

---+ Deployment over multiple networks

To add additional networks to the Apache Tashi cluster, they should be 
brought to the hosts as VLAN network interfaces, attached to software 
bridges. The new network will have to be registered with the cluster 
manager, as detailed in the main installation document. Scheduling of 
virtual machines is open over the cluster, so each host needs to provide 
access to the same networks.

Generally, your network switch will have to be configured to send 
packets "tagged" with the VLAN identifiers for all networks that the 
cluster is to host virtual machines on.

This can be automatically done on start up. For example, a stanza from 
/etc/network/interfaces that configures a bridge for VLAN 11, using 
jumbo frames, will look like this:

auto br11
iface br11 inet manual
  mtu 9000
  bridge_ports eth0.11
  bridge_fd 1
  bridge_hello 1
  up ifconfig eth0.11 mtu 9000

The corresponding /etc/qemu-ifup.11 looks like this:

#!/bin/sh

/sbin/ifconfig $1 0.0.0.0 up mtu 9000
/sbin/brctl addif br11 $1
exit 0

Note that the entire path of a network connection must be configured to 
use jumbo frames, if the virtual machines are to use them.

If you have large numbers of VLANs, and don't want to hardcode them into
each VM host, you can find a sample qemu-ifup in the doc directory. This
script will need to be adapted to your local standards by changing the
basic parameters at the top. This script can then be linked to by the name
Tashi expects them to have. For example, if you have a VLAN 1001, you will
create a link from /etc/qemu-ifup.1001 to this script.

The script will handle the creation of the VM interface, and creation of the
bridge and VLANs if they haven't been created before.

---+ Accounting server

An accounting server is available in the distribution. It will log 
events from the cluster manager and node managers, as well as obtain 
periodic state from the cluster manager on what virtual machines are 
running. It can be started by running "accounting" from the binaries 
directory, and then starting the cluster services.