Bookkeeping Management System.

Hardware requirements for the LHCb Bookkeeping Management System.


Introduction
The conclusions made in this document are the result of the observations made on the server machines during the stress- test of AMGA server and while the Bookkeeping services are running for production.
The AMGA server was running on a dual processor machine (Xeon) of 2.4GHz each with 1 GB of memory. The bookkeeping production machine is a Pentium III of 850MHz with 768 MB of RAM.

Resource consumptions
AMGA has proven to be reasonably efficient in terms of resource consumption during the multi-client connections test. The memory consumption was around 10M per connection.
The only bottleneck to AMGA performance was the CPU which was fully used when 5 client where connected. ( see chart at http://www.physics.ox.ac.uk/users/cioffi/UKmetadata/Oxford/MultiClientsCon.xls). From the observation of the production system I could see that over few months very rarely three users were connected contemporaneously.

On the production machine are installed four python production servers, plus the Tomcat server. The same machine is also used as development machine with many other services running on it. All the services are supported very well by this old machine where a 33% average load is observed. None of these services is absorbing a reasonably amount of memory or CPU.

Hardware requirement
Based on the current use of the system by the Dirac developers and physicists a single dual-core machine as the one used for the AMGA testing will be enough to support the AMGA server and the other production services.
Based on the LHCb computing model where only one user will be the writer of the bookkeeping and all the others are readers, in case more than 5 contemporaneous connections are frequently exceeded, new instances of AMGA, with only read privilege, can be installed easily on separate machines.

Conclusion
It is my believe that a single dual-Xeon machine at 2.4 GHz with 1GB-1.5GB is sufficient to support all the bookkeeping Services till the real data taking from the detector.