CDR Accounts - Creation Procedure

The account under which the CDR software will be installed and run must exist both on the Data Acquisition (DAQ) machine and on the central storage server. Either or both of these accounts may be local or AFS accounts but, in any case, the accounts must have the same Unix uid/gid combination. This will be automatic if an AFS account is used. Where a local account is created in /etc/passwd on the DAQ system, the uid and gid will be the same as the uid/gid of the account name in AFS. The CDR account name should not be used by other group members for interactive work.

It is highly recommended that a local password file entry is used on DAQ systems so that data recording independent of the AFS service.

The account under which the cdr will be run should be created as an AFS account by a group administrator. The account should then be installed on the local machine using the the ccdbuser command ensuring the correct uid/gid combination.

Since the CDR software is controlled by crontab, the account must have permission to execute cron jobs. The mechanisms for cron access or denial vary with the different UNIX variants.

DAQ configuration for CDR

All CDR data is written to CASTOR and there are requirements common to all DAQ systems:

• The CDR software is controlled by a crontab (or acrontab for AFS). Cron/acron must be running on the DAQ machine and the CDR account must have permission to execute cron jobs.
  
  

• The file /etc/shift.conf must be present on the DAQ machine and should be given group write privileges. This will allow CDR support team to make changes when necessary, without the root password.

• The installation of the AFS client software is not required by CDR but its presence on the DAQ does not present any problems. All CDR scripts and executables are local and independent of the AFS file tree.
  

DAQ Storage Requirements

The directory to which datafiles are written on the DAQ is specified as part of the CDR service form. It is managed by the CDR scripts and must be used for that purpose only. Ideally, the directory should be its own Unix filesystem with a size large enough to handle several days of data taking. By using a reasonable disk data buffer on the DAQ, the CDR recording can be more resilient against possible problems with the data network or CASTOR. It also means that, in the event of problems, data taking can continue over a weekend when CDR support may be at minimal level. Disks of 50-300 GB are now commonplace and this kind of capacity is fine for most testbeam applications.

Operating Systems

CDR uses the rfio copy program to transfer data to CASTOR and so only runs on systems for which rfio is supported. Supported OS platforms are HP-UX 10, AIX 4.3, SUNOS5.6, Solaris 7 and 8 and Redhat 6.0 and later versions. Earlier OS versions than these are no longer supported