Application instance not starting ,dispatcher in gray status with DNS error

Trying to start the SAP system and stuck with the error related to DNS.

Error as reported :

Post upgrade I was trying to start the application instance but I was unable to start the SAP instance.
I could see when issuing sapcontrol -nr $$ -function GetProcessList command the dispatcher can be seen in GRAY status indicating it is stopped.

sapcontrol -nr <instance number> -function GetProcessList

<DATE> <TIME>
GetProcessList
OK
name, description, dispstatus, textstatus, starttime, elapsedtime, pid
msg_server, MessageServer, GREEN, Running, 2017 10 26 08:00:50, 4:53:13, 12486
disp+work, Dispatcher, GRAY, Stopped, , , 12488

Identifying the issue

I could see that from the entries when the network check is being performed the conversion/resolution of service to port number is not working fine.Also there were entries were clearly it was indicating there were some issues in the network layer. (OR maybe something was wrong in my network configuration ?)

Troubleshooting

From the GetProcessList output I was confident the issue was with the dispatcher.So my next step was to check in the dispatcher trace file ( dev_disp).

In dispatcher trace file (dev_disp) the entries can be seen as :

*** WARNING => DpNetCheck: NiServToNo(sapdpXX) failed (rc=-3)
*** ERROR => DpNetCheck: NiServToNo(sapgwXX) failed (rc=-3) [dpxxtool2.c 6316]
***LOG GZZ=> 2 possible network problems detected – check tracefile and adjust the DNS settings [dpxxtool2.c 6454]
MtxInit: 30000 0 0
*** ERROR => DpSysAdmExtCreate: ShmCreate (CREATE) [dpxxtool2.c 648]
*** ERROR => dispatcher already running ???? [dpxxtool2.c 649]
*** ERROR => I better EXIT before I do any (more) damage [dpxxtool2.c 651]

 

Here I could notice 2 main functions :

1. DpNetCheck –> This function checks the network configuration.

2. NiServToNo –> This function convert service name to (port) number

The cause of the issue was the services sapdp<instance number> and sapgw<instance number> are missing from the services file.

Resolution <<<< luckily it worked 😉 >>>>

In order to resolve the issue I followed the below steps :

1. Maintain the services sapdpXX and sapgwXX services in services file.

A. Location of services file for linux/unix is as /etc/services
B. Location for Windows OS is under \Windows\System32\drivers\etc\services

 

2. The entries in the services file should finally look like

sapdpXX#32XX/tcp## SAP System Dispatcher Port

sapgwXX#33XX/tcp## SAP System Gateway Port

To get more information on the ports and their usage please see the link TCP/IP Ports of All SAP Products

Post maintaining the entry in the services file I was able to start the system. 🙂

Happy reading 🙂

Feel free to let me know in case any queries.

Regards,
Manjunath Hanmanthgad