storage configuration for cluster

PiotrIr

What configuration is better and why?

MD3000i with 10x450GB HDD I’m going to use RAID 1+0
2x two node clusters (active, passive) connected over iSCSI
- First SQL cluster
- Second Hyper-V cluster
1x stand alone server as Hyper-V host also connected to SAN

As far as I know RAID is faster when you use more disks. So in my opinion the best solution is to create one storage group in RAID 1+0 and on these separated LUNs for VMs, SQL logs, SQL DB. I’m I right or not? What is disadvantage of this configuration?
Should I create separate storage group for each cluster/stand alone server?
Should I create separate storage group for SQL logs, SQL database, Quorum?

Claymoore

You need to separate your logs from your databases in both SQL and Exchange - not just separate LUNs, but separate physical disks. One often-cited reason is that if you ever lose the array that housed your dbs, you would do a restore and replay the logs from the still-functioning log array and you don't lose any of the data that was written after your last backup. The real reason IMHO is for performance. Log writes are linear - one entry right after the other in the log file - so the disk write heads just keep moving to the next block without having to seek all over the disk. DB reads/writes are random - writing and accessing information all over the DB - so the disk heads are always moving. When you start to consider the rotational latency and seek times of all the disks in the array, the performance gains are noticable.

But you don't need 450 GB drives for logs. You should consider smaller, faster drives if your array supports them. If your array holds 15 drives, subtract 1 for a hot spare and 2 for the log mirrored drives. That leaves you with 12 drives for use in a storage pool for SQL and everything else. Someone else could better recommend the best practice for carving up drives for VMs, but you may want to create separate a storage group for them and put SQL on a different storage group. Once you have a storage group for SQL, I don't see any reason why you couldn't create separate LUNs for the quorum and database drives.

PiotrIr

Many thanks for your reply.
My problem is I can’t change configuration so I have to use 450GB SAS HHDs. Because DB is 4GB now and requirement is 40GB so it would be wasting space I would use 450GB mirror HDD for DB. I have hot spare 450GB HDD and 2x72GB in addition.
So does it make sense?
Storage group 2x72 GB (R1) for logs
Storage group 10*450 GB (R1+0) for rest
LUNs:
100GB for DB (to give them more than they need)
2GB quorum SQL cluster
20GB MSDTC – Does it make sense, I don’t know how much space I should use for this?
200GB for shared files folder (wwwroot folder for IIS published on SQL cluater)
2GB quorum Hyper-V cluster
1900GB for virtual machines.

Or let say:
Storage group 2x72 GB (R1) for logs
Storage group 2*450 GB (R1+0) for SQL DB, SQL quorum, MSDTC and Shared Folder
Storage group 8*450 GB (R1+0) for Virtual Machines

I know perfect would be to have separate storage only for SQL but I thought RAID (1+0) from 10 HDDS is always faster than 10xRAID1 volumes?
Once again many thanks for your help.