that one should be only for SQL 2016 and above.No. That's a rule that DBAs are using since at least SQL Server 2005.
we all talking about .mdf and .ndf but how about log ? all data writes to log first and then committed to the data file.The rule is only for data files. There's no sense to create more that a transaction log file since it's sequential writing (the engine can't write in more than a transaction log file at a time).
how about as much tempdb log file as tempdb data file? and all equal size ?
what I know there are only 3 x rules for tempdb:So if you have for example a server with 4 cores in 2 sockets, how many files would you create?
1) number of tempdb file = number of CPU core.
2) number of tempdb file = 1/2 number of CPU core.
3) number of tempdb file = number of CPU socket,
I know in SQL 2016, default number of tempdb file is 8 and we no need to calculate any more, and just keep adding tempdb if tempdb contention is found.This is for facilitate the life on non-DBAs :) And I bet that you don't see there more than one transaction log file, do you?
tempdb data file is parallel write ?Any SQL Server database is, since it has more than one data file.
can you tell me why people would like more than 1 tempdb log files ?Besides you and don't know anybody that like to have more than 1 tempdb log file. The only situation that I can think that justifies a second transaction log file is when the disk is full and for emergency you'll need to create a 2nd transaction log file in another disk for an immediate workaround.
Do you have the exact error message?