Question & Answer
Question
How are port reservations configured for z/OS NFS services when TCP/IP Autolog is used to start the z/OS NFS Server? Also, how can the cancel and restart of the z/OS NFS Server by TCP/IP Autolog be avoided?
Answer
When TCP/IP is configured to start the z/OS NFS Server in the AUTOLOG section, care must be taken when PORT or PORTRANGE definitions for the NFS Server are specified. For every server in the AUTOLOG section, TCP/IP checks to ensure the server is listening on its defined ports once per time interval, unless NOAUTOLOG is specified for the port. The default interval is five minutes. If a server is not found to be listening on any of the defined ports, TCP/IP assumes a server malfunction occurred and takes action to cancel and restart the server.
These actions taken by TCP/IP are captured in SYSLOG and are similar to the following sequence, where MVSNFS is the name of the NFS Server:
CANCEL MVSNFS,A=00AD
IEA989I SLIP TRAP ID=X222 MATCHED. JOBNAME=MVSNFS , ASID=00AD.
IEA989I SLIP TRAP ID=X13E MATCHED. JOBNAME=MVSNFS , ASID=00AD.
BPXP018I THREAD 1961003000000028, IN PROCESS 16842776, ENDED 951
WITHOUT BEING UNDUBBED WITH COMPLETION CODE 0013E000, AND REASON
CODE 00000000.
IEE301I MVSNFS CANCEL COMMAND ACCEPTED
IEA989I SLIP TRAP ID=X13E MATCHED. JOBNAME=MVSNFS , ASID=00AD.
BPXP018I THREAD 1960F12000000027, IN PROCESS 16842776, ENDED 954
WITHOUT BEING UNDUBBED WITH COMPLETION CODE 0013E000, AND REASON CODE 00000000.
IEA989I SLIP TRAP ID=X13E MATCHED. JOBNAME=MVSNFS , ASID=00AD.
BPXP018I THREAD 1956C35000000023, IN PROCESS 16842776, ENDED 956
WITHOUT BEING UNDUBBED WITH COMPLETION CODE 0013E000, AND REASON CODE 00000000.
...
IEF450I MVSNFS MVSNFS - ABEND=S222 U0000 REASON=00000000
$HASP395 MVSNFS ENDED
IEA989I SLIP TRAP ID=X33E MATCHED. JOBNAME=*UNAVAIL, ASID=00AD.
S MVSNFS
The z/OS Network File System Guide and Reference shows sample PORTRANGE statements that can be used to reserve port numbers for the NFS Server and its services. The following example is provided:
PORTRANGE 2043 7 UDP mvsnfs ; Reserved for startup JCL, mvsnfs
PORTRANGE 2043 7 TCP mvsnfs ; Reserved for startup JCL, mvsnfs
TCP/IP cancels and restarts the NFS Server every 5 minutes (by default) when:
These actions taken by TCP/IP are captured in SYSLOG and are similar to the following sequence, where MVSNFS is the name of the NFS Server:
CANCEL MVSNFS,A=00AD
IEA989I SLIP TRAP ID=X222 MATCHED. JOBNAME=MVSNFS , ASID=00AD.
IEA989I SLIP TRAP ID=X13E MATCHED. JOBNAME=MVSNFS , ASID=00AD.
BPXP018I THREAD 1961003000000028, IN PROCESS 16842776, ENDED 951
WITHOUT BEING UNDUBBED WITH COMPLETION CODE 0013E000, AND REASON
CODE 00000000.
IEE301I MVSNFS CANCEL COMMAND ACCEPTED
IEA989I SLIP TRAP ID=X13E MATCHED. JOBNAME=MVSNFS , ASID=00AD.
BPXP018I THREAD 1960F12000000027, IN PROCESS 16842776, ENDED 954
WITHOUT BEING UNDUBBED WITH COMPLETION CODE 0013E000, AND REASON CODE 00000000.
IEA989I SLIP TRAP ID=X13E MATCHED. JOBNAME=MVSNFS , ASID=00AD.
BPXP018I THREAD 1956C35000000023, IN PROCESS 16842776, ENDED 956
WITHOUT BEING UNDUBBED WITH COMPLETION CODE 0013E000, AND REASON CODE 00000000.
...
IEF450I MVSNFS MVSNFS - ABEND=S222 U0000 REASON=00000000
$HASP395 MVSNFS ENDED
IEA989I SLIP TRAP ID=X33E MATCHED. JOBNAME=*UNAVAIL, ASID=00AD.
S MVSNFS
The z/OS Network File System Guide and Reference shows sample PORTRANGE statements that can be used to reserve port numbers for the NFS Server and its services. The following example is provided:
PORTRANGE 2043 7 UDP mvsnfs ; Reserved for startup JCL, mvsnfs
PORTRANGE 2043 7 TCP mvsnfs ; Reserved for startup JCL, mvsnfs
TCP/IP cancels and restarts the NFS Server every 5 minutes (by default) when:
- the PORTRANGE statements are specified as shown in the example,
- the NFS Server is started in the AUTOLOG section, and
- all of the NFS services are not active on the reserved ports.
One method of dealing with this problem is to reserve only the ports that are needed by the NFS services that are active. However, this approach requires configuration changes to reserve the necessary ports when new NFS services are deployed and allows for the possibility of the necessary ports to be used by other applications or services.
An alternative approach would be to specify the port reservations as suggested in the example provided in the z/OS Network File System Guide and Reference but to add the additional NOAUTOLOG parameter to the PORTRANGE statement. The following examples show syntax used in the AUTOLOG section and for the PORTRANGE statement that uses the NOAUTOLOG parameter:
AUTOLOG 5
...
MVSNFS ; NFS Server
...
ENDAUTOLOG
PORTRANGE
2043 7 UDP MVSNFS NOAUTOLOG ; MVSNFS (details in /etc/services)
2043 7 TCP MVSNFS NOAUTOLOG ; MVSNFS (details in /etc/services)
This solution has the negative consequence of preventing TCP/IP from restarting the NFS Server when a failure occurs, which would be a beneficial service.
An alternative approach would be to specify the port reservations as suggested in the example provided in the z/OS Network File System Guide and Reference but to add the additional NOAUTOLOG parameter to the PORTRANGE statement. The following examples show syntax used in the AUTOLOG section and for the PORTRANGE statement that uses the NOAUTOLOG parameter:
AUTOLOG 5
...
MVSNFS ; NFS Server
...
ENDAUTOLOG
PORTRANGE
2043 7 UDP MVSNFS NOAUTOLOG ; MVSNFS (details in /etc/services)
2043 7 TCP MVSNFS NOAUTOLOG ; MVSNFS (details in /etc/services)
This solution has the negative consequence of preventing TCP/IP from restarting the NFS Server when a failure occurs, which would be a beneficial service.
The following syntax can be used to:
- allow TCP/IP to monitor only port 2049,
- allow TCP/IP to restart only the NFS Server when a true failure occurs, and
- reserve the ports of all NFS services.
AUTOLOG 5
...
MVSNFS ; NFS Server
...
ENDAUTOLOG
PORT
...
2049 TCP MVSNFS ; NFS Server -- see PORTRANGE also
...
PORTRANGE
; MVSNFS note: 2049 TCP in PORT instead so TCP/IP monitors & restarts
2043 7 UDP MVSNFS NOAUTOLOG ; MVSNFS (details in /etc/services)
2043 6 TCP MVSNFS NOAUTOLOG ; MVSNFS (details in /etc/services)
Related Information
[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SWG90","label":"z\/OS"},"Component":"5695DF121 - DFSMS\/MVS NETWORK FILE SYSTEM SERVER (NFS)","Platform":[{"code":"PF035","label":"z\/OS"}],"Version":"All Versions","Edition":"","Line of Business":{"code":"LOB56","label":"Z HW"}}]
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Modified date:
03 September 2021
UID
isg3T1010362