I inherited a performance investigation problem where a SQLServer 2008( and also 2012 ) database has its Data, Indexes and Log files all on a single drive D: The D: drive is actually part of a SAN. I don't have much else at this time in the way of details.
My recommendation is to have a minimum of 3 drives, 1 for Data, 1 for Indexes, 1 for Transaction Log. There is a lot more we can do here, this was just where I wanted to start as we look into all the possible problems there could be.
My intuition is even if they made more "logical disks" on the SAN and made those available to the OS and SQLServer, then we would be further ahead but I am met with complete resistance, stating that its the same thing since they are all on a SAN, so load is distributed.
Maybe they are correct, but I don't think so. I don't really care who is correct, I am trying to find a specific article or something that will clear this up one way or another. I can't seem to find the perfect answer to this.
To me, even though the single D: drive is sitting on a SAN, to the OS it is a single drive and would have a "single buffer" between the OS and the SAN, and would be a candidate for contention. I have no real experience with SAN technology so if I am wrong, I want to understand.
Thanks for any guidance.