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OMVS Startup in zOS and Logs

USS has two sides that it needs to work on. An MVS side to interact with the MVS system and the second side to interact with Unix side USS.

Together the OMVS and BPXOINIT each manage a different aspect of USS. OMVS interfaces with MVS and BPXOINIT starts and helps manage processes running in USS.

OMVS starts the UNIX file system services on the mainframe.

The OMVS address space is the 'MVS' hat. It is started first and establishes the layer USS layer that communicates and co-ordinates resources with the MVS side of the zOS system.

At IPL time, the OMVS address space processes the BPXPRMxx member and performs all tasks it contains (setup filesystems, limits, networking, mounts.. etc).

After IPL, it helps to manage interprocess communication, inter-system filesystem sharing, resource/storage management.

OMVS starts and invokes BPXOINIT

BPXOINIT address space (started by the OMVS STC) initializes the UNIX environment.

BPXOINIT is the first 'unix' process to run in the system (it is PID 1). Among other things also invokes 2 tasks ETCINIT and ETCRC.

ETCINIT does is invoke the USS shell command '/usr/sbin/init'. The init command reads the file /etc/init.options and will perform some environment setup before it fires off the initialization script /etc/rc.

ETCRC executes the commands in /etc/rc which has the statements to initialize the daemons like SYSLOGD, inetd and so on.

SYSLOGD has the statements that help us to find the logs for ftp, sshd, fdrupstream and so on.

The inetd daemon provides service management for a network. For example, it starts the rlogind program whenever there is a remote login request from a workstation.Inetd -- INETD is a daemon that listens for incoming TCPIP requests (on specific ports) and then launches applications to handle those incoming requests. Newer servers do not tend to use INETD anymore. FTP, SFTP and SSHD can all run as standalone servers, we may not be running these daemon.

sshd starts and ends typically and in general. A forked copy of the daemon will be left running, which is normal. Sshd is for SFTP environment.

ftp* tasks setups the environment for the ftp protocol it can be normal ftp or secure ftp using TLS. FTPS is for secured ftp over tcpip using TLS.

BPXAS fork task starts every time there is an OMVS activity by users or app.

Log files:
  • ETCINIT and ETCRC logs are written to either syslog or few specific messages are written to /etc/log.

  • Users can find the history of the command that they have issues @ /u/userid/.sh_history. Userid is the home path defined to users omvs segment.

  • FTP/SSHD/OMPROUTE and other can be found in the SYSLOGD conf file in general /etc/syslog.conf (or check the /etc/rc for the syslogd statement).

  • In /etc/syslog.conf *.FTP*.*.* /var/log/%Y/%m/%d/ftp --- this refers to /var/log/year/month/day/ftp file or you can also have it as /tmp/ftp and so on.

Published on May 4, 2020 by - Yugesh Pothuru

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  1. Yugesh Pothuru 
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