Hi Livecache Experts,
We recently had an issue with starting the livecache. I found out that when the livecache was stopped, they didn't stop the x_server process. When they tried to bring up the livecache, it won't come up. They tried to perform the x_server stop, kill sdb process then start x_server again but the livecache won't come up still.
So I ended up restarting the livecache server itself then start the x_server - now everything is started cleanly. Then I was able to bring the livecache.
My analysis on this is when they tried to bring up the livecache for the first time, it didn't come up since x_server wasn't stop and started cleanly. there is a kind of miscommunication between the two. Then even when you tried stopping and starting x_server after livecache start failure, it doesn't work because its already too late to do that since livecache doesn't recognize the "sdb" user/processes anymore. It made sense to me because that is the error we encountered when trying to bring up the livecache, we get "sdb user unknown"
Only when we restarted the server itself and perform a clean start then it worked. Also have to rename the dbm.shi dbm.shm processes as mentioned in https://scn.sap.com/thread/3262926
Questions:
1. Is it required to stop the x_server and kill sdb processes when you stop the livecache?
2. What is their dependency on each other?
3. What happens when x_server is not stopped then you try to bring up the livecache? (I want someone to elaborate what happens in the background.)
4. Why is there a need to rename the dbm.shi and dbm.shm as mentioned in this thread - https://scn.sap.com/thread/3262926?
Everything is working fine right now, I just wanted this incident to be documented with the correct information and raise awareness to prevent this type of issues to happen again.