During the last few weeks we’ve faced some serious problems with one of our TM1 production servers. The production server instance kept crashing on daily basis and without giving any clear reason why. We arranged surveillance by using Windows’ Performance Monitor and collected some system data but found nothing suspicious there either. The only clue were the last lines in tm1server.log just before the server crashed:

tm1server.log just before the crash

So, instead of trying to find a needle in a haystack we went through the rules of the last mentioned }ElementAttributes cubes and found out that in three of them a built-in-and-safe-sounding function LONG was used. At the time of development it may have been a good idea but nowadays at least with version 9.5.2 it is definitely a no-go: PM38586: LONG FUNCTION IN TI CAUSES TM1-SERVER HANG/INSTABILITY

IBM’s recommendation is to upgrade to version 10.1.0 but that was not an option for us at the moment so we needed to find a workaround. Now after fixing the rules with a workaround that avoids using the LONG function seems to have done the trick: production server is stable again and does not crash. So, my strong recommendation is not to use LONG function in rules if you are running TM1 version 9.5.2 or lower.