II - CTA services

Basic services and files:

CTA is mainly composed of the following daemons in order to work:

• cta-rmcd: The remote media changer daemon is a TCP/IP server which controls the robots in the tape libraries. It must be run locally for security reasons: it only listens to the localhost network. It includes a device driver for the drive and one for the library. The config files of this service are:

  - /etc/cta/cta-rmcd.conf - /etc/sysconfig/cta-rmcd - /etc/systemd/system/cta-rmcd.service The logfile of this service is located at /var/log/cta/cta-rmcd.log.

• cta-taped: The tape daemon that manages the tape drive and it is in charge of the entire tape sessions, either to write or to read data to/from tapes. The config files of this service are: -/etc/cta/cta-taped.conf -/etc/sysconfig/cta-taped -/etc/systemd/system/cta-taped.service The logfile of this service is located at /var/log/cta/cta-taped.log. As you will notice in the log, this daemon it's composed of a main process and a bunch of sub-processes that handle reporting, drive and maintenance tasks.

• cta-frontend: This xRoot daemon is the one in charge of establishing a connection with the cta admin cli. This is done through Kerberos authentication. It also manages SSS keys to authenticate communication with tape servers and other EOS daemons. The config files of this service are: -/etc/cta/cta-frontend-xrootd.conf -/etc/sysconfig/cta-frontend -/etc/systemd/system/cta-frontend.service The logfiles of this service are located at /var/log/cta/cta-frontend.log and /var/log/cta/cta-frontend-xrootd.log .

• cta-frontend-grpc: This daemon is the one in charge of connecting dCache and CTA at the moment. It just receives and enqueues the archive/retrieve requests coming from the dCache pools. The config files of this service are: -/etc/sysconfig/cta-frontend-grpc -/etc/systemd/system/cta-frontend-grpc.service This daemon logs at /var/log/messages, but you can always redirect these logs with a simple syslog rule.

On dCache's side:

• dcache-cta plugin: the nearline storage plugin for dCache, is responsible to enable communication between the dCache pools where it is installed and the cta-frontend-grpc service.