The Calar Alto Computer System
(Last updated on June 2009)
It is known that a scientific centre must have the latest technology. Calar Alto Observatory has made a big effort in the past, and it is still doing it, for ensuring an advanced computer environment to all the staff (scientific, technical and administrative) working at the Centre. This article will suffer an evolution together with Calar Alto Computer System, so you can see the state of the art of our system while the time passes.
Let's start with some of our history to see the evolution from the initial steps into the actual situaton.
Since early 90's the Calar Alto Computer System has grown in a very fast way. We have grown from the old PDP 11, passing through SUN Ultra/Fire workstations, to the actual PC machines and virtualized environment. At the beginning, we created the first coax network, sharing a 10Mbps. bandwidth between all the systems. That was a big advance, as at that moment, we entered into the communications world. This network was moved later into a switched Twister Pair / Fibre Optics Giga/Fast Ethernet allowing the new fast workstations to work with dedicated 100Mbps. Last two years we modified a lot all internal communications, as we see later. The external network attached to the Internet has also experienced a big jump, from the starting 9600 Bps. bandwidth, moving to 8Mbps. microwave link first and then to the actual 200Mbps (symetrical) using the same microwave technology. As well the Operating Systems are been replaced frequently for having the latest utilities and facilities. In this aspect we have moved from the initial SunOS 4.1.3 to Solaris 2.4, and from that one to Solaris 8, Solaris 9 and Solaris 10. As you can see, we covered different steps until the actual state. Once on the new century, we started another big movement: the service transition between Solaris to Linux. This transition is finished today but, as the instrumentation computers still use Solaris, this could take some time until all Solaris machines are gone. But the effort of giving the main services (DNS, mail, applications, DHCP, printer queues...) under Linux operating environment is finished already.
This article tries to show all the actual Computer System at Calar Alto (June 2009).The intention in not going deep into the technical concepts of all the system. This would cover near a book. The idea is giving a general understanding of the whole system, how it is designed and how it is working at the present.
As a complement of this article, you can see here the yearly news. On those pages, you can see part of the recent Computer Department history. The first news release was for year 1999. Since then, until the present, you can see the evolution of the CAHA Computer System.
It is time now to see a general overview of the internal network that joins the whole Information System.
On the next figure, you can see how the Calar Alto Internal Network is on the moth of June of 2009.
We are working at present on this scheme, so probably, when you read this, we will have already upgraded some of the above links. The final idea is having the complete main ring (the STP ring) at a 10Gbps bandwidth and the 1.23m and the hotel running at 2Gbps. But we are working also on having a real semi-meshed network, so if some of the building is down, the rest can still working.
On the above figure, you can see also that the most important points of the network have 1Gbps direct connection to the computer. This will be true also for other parts that, at the moment, only have 100Mbps connection to computers (i.e. the library)
Our installations comprise the whole Calar Alto Campues and a central office in the middle of Almería city, mainly for administrative purposes. At the beginning, that office was only connected to Internet via independent modems on each of the computers working there. No network between them. From late February 2001, there is a Microsoft Network running on that place, with all the PC's connected. After the network was set up a Cisco 801 was prepared to connect the Office with the mountain network via a permanent ISDN link. Almería's Office Network is a Private Network and addresses are converted via NAT protocol on the router. That network also has a DHCP server, so any person visiting our office with a laptop can use our network resources.
Although virtualization is not a real new technology, it is now taking an important role in data centers. The benefits are multiple. Virtualization is allowing servers consolidation. In such way, a physical server can have multiple virtualized servers, reducing costs and giving some important functions to the IT managers. One of them is the ability of moving virtualized servers from one physical machine to another in case of the first physical computer fails.
All of these have beein implemented in Calar Alto last years. We have moved from a big number of physical servers into a reduced one that have all the old servers virtualized inside.
Next figure shows how were servers arrangement before virtualization:
And next one presents how everything is after virtualization:
As you can see, now we have three big physical computers that hold all the virtual servers inside. But the main advance is that we can move a virtualized server from one physical machine into another. In fact, the third computer holds all spare servers. If we have problems with a virtualized server in a server, we can stop it and start it on the spare physical computer so we can continue working while fixing problems on the original virtual server. Next step will be Windows computers virtualization
We are giving to our users, all kind of services such as DNS, DHCP, Mail accounts, etc...
Dinamic IP (DHCP) is offered everywhere at our Centre. This service will suffer some modifications soon. When this happens, I'll inform about them in this pages. One part of this service is the wireless connections. You have wireless at the Hotel Hall and at the Laboratory.
Videoconferencing system is also allowed and we belong to the Global Dialing Scheme (GDS), with a linux gateway running on a special server.