Sql-server – Putting SQL Server data files in a different partition

But, from reading into it more, separate physical disks for mdf and ldf files don't really apply when it comes to SSD's. Correct?

The original reason for splitting log and data files off onto seperate disks was 2 fold - latency and bandwidth on the drives.

SSDs don't remove these restrictions, but they do decrease/increase the limits quite significantly (7.9ms for a read with a single HDD vs 0.1ms for a read in a single SSD, roughly).

So ultimately yes and no - it doesn't apply AS MUCH as with HDDs, but those limits are still there and can still be met. It all depends on your workload.

Is my "thinking" setup good or just simply a waste (i.e. no reason to separate out tempdb) where I now have an extra SSD to make use of elsewhere?

Assuming that

• You have 3 physical SSD's
• You have 1 physical HDD
• You need the data to be redundant, but not necessarily the system itself

Your proposed setup would have a few issues (as mentioned before), and a single drive failing is the main one.

You could go for something like this.

Single 7200rpm drive - Windows OS
RAID 5 array (3 SSDs) - Broken down into 4 drives (D for Data, L for Logs, S for Swap and T for Temp)

OR

Single 7200rpm drive - Windows OS
Single SSD - Temp and Swap
RAID 1 array (2 SSDs) - Data and Logs

It's personal preference of mine offloading Windows onto a non-SSD drive when you only have a limited number, but this entirely depends on what the server is doing and how much of a risk you're willing to take.

In my extensive testing of cloud SQL on cloud servers (rackspace cloud, to be specific), I found that splitting the ldf and mdf to distinct block storage volumes made a significant improvement in performance. I achieved really hot performance by putting the ldf on an SSD based block storage volume and the mdf on a standard block storage volume.

Ultimately, of course, a block storage volume is a shared SAN somewhere. And local "instance" storage is on the hypervisor itself. So the hardware topology of your cloud environment will dictate what config will work best.