Application server gone down

Question

Dear all,
Our Prod is cluster environment ,
PRODORADB ---> DB
PROD CI ---> CI
PROD APP1 ---> Application server1
PROD APP2 ---> Application server2.
During the monitoring , i found one of One of my server gone done (PROD APP2 ---> Application server2) .
I dont know what reason PROD APP2 ---> Application server2 gone down, pls suggest .
I have tried to make up PROD APP2 ---> Application server2 , its showing started and i have checked R3trans -d. its shows connected with DB, i have logged through sapgui ,its shohs partner not reached (host 10.54.145.34, service sapdp00) but its not started . pls check the below logs .
PRDAPP2:irpadm 2> startsap
Checking IRP Database
ABAP Database is running
Starting SAP-Collector Daemon
This is Saposcol Version COLL 20.95 700 - AIX v11.65 5L-64 bit 090118
Usage:  saposcol -l: Start OS Collector
        saposcol -k: Stop  OS Collector
        saposcol -d: OS Collector Dialog Mode
        saposcol -s: OS Collector Status
The OS Collector (PID 389208) is already running .....
saposcol already running
Starting SAP Instance D00
Startup-Log is written to /home/irpadm/startsap_D00.log
Instance Service on host PRDAPP2 started
Instance on host PRDAPP2 started.
PRDAPP2:irpadm 3> R3trans -d
This is R3trans version 6.14 (release 700 - 09.04.10 - 11:26:00).
unicode enabled version
R3trans finished (0000).
PRDAPP2:irpadm 4>
Kindly suggest

Answer 1

Check if you have all the sap processes running or not ? (ps -ef | grep <sid>adm).
If you dont find them ,  check the logs under /usr/sap/<SID>/<Instance>/work , you surely should find why they got killed     after the start.
If you see the processes running , that means your apps instance is not communicationg with  the message server , in that case you should check your profile ,etc.
Regards,
Neel