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?
In short, there probably isn't a way to be truly sure. What I would say (I am a SAN admin), is that if your applications are performing up to your expectations, don't worry about it. If you start to see performance issues that you believe could be related to SAN/Disk IO performance, then it might be wise to inquire. I do not use much HP storage like you do, but in the IBM/NetApp world I can say from experience that there aren't many options which would allow you to configure it "poorly". Most enterprise storage these days takes a lot of the guesswork out of building raid arrays, and doesn't really let you do it wrong. Unless they are mixing drive speeds and capacities within the same raid groups you can rest-assured in most cases that your disk is performing fine.
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.)
Load testing should be plenty reliable. Just keep in mind that when you are load testing one box, that being on a shared SAN/Disk Array that its performance can (and will) be affected by other systems using the same storage.
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)
It can. It is not all about the disks, or which disks, the servers are on. All of the data is being served up via a disk controller, and then a SAN switch. The performance you will see greatly depends on how the disk controller is connected to is corresponding disk shelves, and the corresponding SAN. If the entire array connects to the backbone SAN on one single strand of 4gbps fiber, then clearly the performance will be impacted. If the array is connected across two redundant SAN's which are load balanced, using trunked links, then it would impossible for exchange alone to suck up too much bandwidth. Another thing which needs to be considered is how many IO/sec the array is capable of. As long as the array and the SAN it is connected to are scaled correctly, heavy IO in other parts of the SAN environment should not impact your SQL performance.
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?
That is probably a matter of preference, and also greatly depends on how your storage admins configure it. They could give you three LUNs in the same array or volume, in which case its all the same anyway. If they gave you individual LUNs on different arrays, in different volumes (physically different disks), then it might be worth it for you to separate them.
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?
I don't imagine your storage admin would change the raid level in order to free up space. If he would, then he should probably be fired. Space concerns can lead things to be configured differently, but not normally in a performance-impacting way. They might just become a little more tight about how much space they give you. They might enable features such as data de-duplication (if the array supports it) which can hinder the performance of the array while the process runs, but not around the clock.
I'm sorry but I have to strongly disagree with ynguldyn, what they say might be true for other disk arrays but this is an EVA and I'm a through-and-through EVA-guy. We have dozens of them, all models and sizes, and there's literally zero benefit breaking up disk-groups into smaller units, they're designed that way and offer best performance when in one big block. In fact splitting disk-groups slows EVAs.
For example one of my newer 8400's has 16 shelves of 12 x 450Gb 15krpm FC disks, using iozone we tested it split into two disk-groups and it was 20% slower across the board of tests in this manner compared to a single disk group.
Also the array isn't broken into RAID types at the disk-group level, so it's not RAID10 for everything, individual vdisks (LUNs) have a particular RAID level but the disk-group itself only has the option to pre-allocated one or two hot standby disks (leave this at one by the way). This way you can give DB logs, MSDTC, Quorum etc. LUNS R10 and choose how your data and backup LUNs are setup based on your performance requirements (personally I use R10 for all data and R5 for backups but that's your choice). Oh and it's much quicker, and safer, to keep all your different DB data types in separate LUNS ok :)
If you have any follow-up questions regarding EVA's/XP's or other HP storage feel free to come back up me ok.
Best Answer
With regards to Microsoft's docs you should go with either local storage, or shared storage or Microsoft Storage Spaces Direct.
Assuming you what achieve availability for MSSQL Server, I would suggest you go with local storage, identical setup for each host wich would provide you same performance for the case of node failure.
Go with shared storage if you would go with MSSQL FCI.
As for SAN, its SPoF. IMHO