Once upon a time, I built my own SQL servers, and had control over drive configuration, RAID levels, etc. The traditional advice of separation of data, logs, tempdb, backups, (depending on budget!) was always a pretty important part of the SQL server design process.
Now with an enterprise-level SAN, I just request a specific amount of drive space for a new SQL server, divided into logical drives for data, backups, and fileshares. Certainly makes my job easier, but there is a part of me that doesn't feel completely comfortable that I can't really peek "behind the curtain" to see what is really going on back there.
My understanding is that the SAN team doesn't configure different "types" of drives any differently (optimizing data drives for random access vs log drives for streaming writes). Some of this may depend on the SAN product itself (we have an HP XP12000 and an HP XP24000), but I've been assured that the HP software does all sorts of dynamic performance configuration (watching for IO hotspots and reconfiguring on the fly to optimize those LUNs), so that the app teams and DBAs don't need to worry about any of that stuff. Something about "spreading the load of all the servers over a huge number of spindles" or something like that.
Without making enemies on the SAN team, how can I reassure myself and the application developers that our SQL servers aren't suffering from poorly configured storage? Just use perfmon stats? Other benchmarks like sqlio?
If I load test on these SAN drives, does that really give me a reliable, repeatable measure of what I will see when we go live? (assuming that the SAN software might "dynamically configure" differently at different points in time.)
Does heavy IO in one part of the SAN (say the Exchange server) impact my SQL servers? (assuming they aren't giving dedicated disks to each server, which I've been told they are not)
Would requesting separating logical drives for different functions logical drives (data vs log vs tempdb) help here? Would the SAN see the different IO activity on these and optimally configure them differently?
We're in a bit of a space crunch right now. Application teams being told to trim data archives, etc. Would space concerns cause the SAN team to make different decisions on how they configure internal storage (RAID levels, etc) that could impact my server's performance?
Thanks for your thoughts (similar topic briefly discussed in this SF question)