DB2 : Slow connections to database server from remote applications ? Problem with DNS lookup.
Priyanka Joshi 270003HTNX Visits (10499)
Sharing the list of steps we took to isolate(narrow down) the problem area, find the root cause and fix it.
Some primary checks to help isolate this case :
Got following information :
1> Problem was originally seen with the connection from the application server, and later while connecting through SAP (R3trans).
2> Local connection to DB2 server using command prompt was quick.
3> Remote connection from (remote) command prompt was slow as well.
Inference : So the slow connection issue was for all remote connections.
From experience we know that, most times if a slowness is detected for remote connections, it is related to some system(OS) issues in accessing host by name or authentication slow etc.
1> Check if there is a delay in opening /etc/hosts.
Not in our case.
2> Check if the DNS lookup is slow.
check the following :
In our case, issue was caused by an old DNS domain which was decommissioned and was still in the NFS server list.
After removing that DNS entry, connections to database from application (SAP-R3trans) were very fast.
3> Lastly check for network problems like congestion's, lags etc. in connections.
db2fodc -hang full
This will run for some time. If it runs for more than 30 mins please terminate it.
db2support <output dir> -d <database_name> -c -s