Rapporto Tecnico, Anno 7, n° 42 maggio 2012

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Architecture

Our solution is a two-server architecture: back-end server to host repository and java
applications and front-end server for public access to objects. The servers are virtual machines
guested on a hypervisor.
The storage for repository and virtualized infrastructure is a HA two-node active/passive cluster
deployed with open source software.

2.1 Infrastructure
The whole project is realized at CNR Piedmont Network Infrastructure administered by CerisCNR IT Office. The infrastructure includes networking equipments, servers and offers core
network services to CNR structures in Piedmont.
Some keywords to describe our experience: VLANs, IPv6, SAML2 SSO, Virtualization,
Clustering, Mail server, File server, Wireless.
• Virtualization
There are many reasons to choice virtualized deployment: high availability provided by
redundant hypervisors, simple maintenance operations, automatic backup, direct portability.
The hypervisors are connected to VLANs so virtual machines can have one or more interfaces,
each of them connected to a different subnet.
The HA cluster is the backup storage for hypervisor virtual machines, in case of failure they
could be run from cluster to reduce down time.
• Storage
The HA storage is our deployment of a open-source cluster. It provides storage for users and
network services by iSCSI connected partitions.
Virtual machine system partitions are on local storage of hypervisor and daily scheduled backup
on cluster. Data partition of repository server is on the cluster directly attached to server by
iSCSI protocol.
The cluster is deployed on Linux OS (Ubuntu 10.04 LTS) using Corosync, Pacemaker and
DRBD as main components for cluster orchestration, resources administration and data
mirroring.
More details on cluster and maintenance in Ceris-CNR technical report No. 37 “Storage in HA:
cluster attivo/passivo open source” and No. 41 “Storage in HA: manutenzione ordinaria e
straordinaria”.

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