Where to place tempdb and logfiles I have fallowing configuration for my SQL 2014 server:


SSD RAID 1 - for data files
SSD RAID 1 - for tempdb? logfiles?
HDD (SAS 15K) RAID 1 - for tempdb? logfiles?


I noticed that sql uses tempdb quite heavly and I wonder how shall I place the logfiles and tempdb to optimize the throughput (the application is not very write intensive). Does it make sense to put logfiles and tempdb on the same SSD array or I should better use the HDD array for logfiles?
RAID 1 is less suitable for any of Data file, log file and tempdb file. Although RAID 1 provides redundancy by mirroring and also provides bit of a fault tolerance it is kind of outdated with arrival of RAID 5 and RAID10(or RAID1+0). Best is to keep data, log and tempdb on differnt physical drives which are configured either in RAID 5 or RAID10. RAID 10 is more preffered but is costly as compared to other RAID technologies.

If you have restriction with RAID 1 you can use it but then make sure you separate data,log and tempdb files on different physical drive to avoid I/O contention.

Above suggesstion were given because you asked about seggregating files. In many environment because I/O load is relatively less data and log files are kept on same drive, even tempdb is placed on same drive where other files are present. According to surrounding/env/load  we can seggregate files to get optimum performance.