IN THE MINUTES OF THE 22.11.2005

CMS: In the GDB the 3D plan had two baselines: replication using Oracle to Tier-1, and replication still undefined to Tier-2 centers.
CMS uses data streaming of Oracle between online and offline, and this is being tested with the help of the IT team at CERN. For distributing read-only data using replication of queries, CMS is evaluating a solution base on FroNtier and Squid and is working on this with the 3D project and some regional centers. CMS will decide in Spring 2006 which technologies to use.

REPLACED WITH:

3D is for the first six month of production starting in March support
two different distribution techniques with complementary deployment
features:

- Oracle Streams for data transfer between online and offline (ATLAS,  CMS,
   LHCb) and between Tier 0 and Tier 1 (ATLAS, LHCb). This solution  offers
   transactionally consistent replication (asynchronous) but  requires a database
   services to be offered by the sites. ATLAS is planning to  complement this
   with POOL and/or Octopus based data copies into MySQL/SQLight  databases
   at Tier 2.

- FroNtier/squid (CMS) for read-only  transfers between Tier 0, 1 and 2
   and distributed caching of database data. This approach does not  require
   to run a database server outside CERN (deployment of squid is  considered to
   be minimal effort) but the cache consistency impact on  applications (possibly
   stale data in squid caches) needs validation by the experiments.

Both technologies are considered by ATLAS, LHCb and CMS as fallback  for their
initially different baseline.