>I did mean Hekaton but...
>- in message header is MS SQL server 2014
>- you wrote "MS SQL Server 2012" in another message

Yes, this is because I work with a lot of products. My default is 2014 but for that particular one, it is 2012.

>If you have MSSQL 2012, you have not more choices
>- SSD disk (another message)
>- One disk for data, second disc for indexes, third disc for log, forth disc for temp db

Presently, we have one disk for the data and indexes, and another disk for the log.

I never heard having the index files on the same disk as the data would be a factor. Could there be really a factor by sharing those files on the same disk? It is true SQL Server would make more usage of that disk if it has to populate the data and update the indexes at the same time.