2. General questions
Q1 How much will
it cost to use the CDR service
The use of the CDR service itself is free
of charge. Experiments will, however, have to pay for the use of the
magnetic tapes on which their data will eventually be stored. For
the present, data storage on magnetic tape is charged at the rate
of ~2 CHF/GB. Only the total volume of data is charged for, not the
actual number of tapes used. The cost is calculated at the end of
the year. Experiments whose data rates are low, typically <3-5 MB/sec,
will be able to use the CDR public servers to write their data to
CASTOR. Experiments anticipating data rates > 5MB/sec will need
to purchase disk server(s) to be used as CASTOR and/or analysis
servers. The cost of this is borne by the experiment.
Q2 What are the
system requirements for using CDR
See the CDR section
Configuration and System
requirements. Supported OS platforms are HP-UX 10, AIX 4.3,
SUN 5.6, Solaris 7 and 8 and Redhat 6.0 and later versions. Earlier
OS versions than these are no longer supported.
Q3 Who
do I contact for help or support?
Send an email to the mailing list cdr.support@cern.ch.
Q4 Do I need AFS installed
on the DAQ to run CDR ?
AFS is not necessary in order to run CDR. Where
AFS is installed, it is recommended to have local copies of the
executables on disk rather than running executables out of AFS.
The same applies to dynamically shared libraries. Local copies make
the CDR independent of irregularities in the AFS service.
Q5 What account does
CDR run under ?
CDR runs under its own dedicated account. The
account name should be registered as an AFS account and it is strongly
recommended that a local entry in /etc/passwd be created with same
uid/gid combination.
Q6 Does CDR run
over the winter shutdown period ?
No. However, experiments wishing to run during
this period should contact cdr.support@cern.ch
to see if something can be arranged.
Q7
What should be done at the end of a run
Contact
cdr.support@cern.ch so that details can be finalised.
Q8 What resources does
CDR consume
The main activity of CDR is the remote file I/O
copy process which reads a local file and writes to the castor staging
server. The rfcp program is multithreated but for all testbeams,
only one copy of the process runs at a time.
In addition to the rfcp process, there are several
scripts which run periodically, typically every few minutes. These
scripts are concerned with logging and file cleanup and do not create
any significant load.
Q9
Can CDR be used with Objectivity and ROOT ?
Yes. In general CDR only copies files from the
DAQ to tape storage in CASTOR. Modified versions of the CDR scripts
have been developed to handle Objectivity databases but these are
specific for individual experiments.
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