Best drive configuration for terminal server

We are having IO performace issues on a busy terminal server that currently has 2x10k RPM drives running RAID1.  We intend to replace with 6x15k RPM drives.  The users mostly run IE, Outlook, Excel, MAS90 accounting.  
We are trying to decide whether to put all 6 drives in a single RAID0+1 array or put the OS and userprofiles on 2 disks at RAID1 then run the accounting app and shared files off the other 4 at RAID0+1.  I argue that since it's all going through one controller, putting all 6 in one array with 1 logical drive will yield the best performance because it's more spindles handling a given amount of IO, my collegue thinks that we will get better performance by separating into 2 logical drives.  
Thoughts?  (it's an 8 core dell with PERC5/i and 16gb RAM)

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robertstevensAuthor Commented:
Or even two RAID5 arrays?  We are open to suggest, performance is key.
Keep the current drives for the Operating system
Build an RAID10 (or raid 0+1) where you should put the MAS90 Accounting and database (probably you using an SQL server)
With the rest of the money you can add more memory, this will improve also th I/O (the system will use it to cash the data for users)

What kind of operating system do you use? It is recomandable tu use a 64bit operating system for the best memory usage.
robertstevensAuthor Commented:

Thanks for the response.  The RAM usage currently stays below 8gb so I doubt more would help. . .  I guess the real problem is we don't know precisely what process is causing the problem.  The thing just freezes for everyone, all at once for up to 3seconds when under heavy load.  I would hate to find out it's IE caching after moving the whole accounting app over to a new logical drive. . .

Could someone please explain why it would be faster to have 2 logical drives and spread the load over the two when data is going through the same controller?

BTW, its windows 2003 r2 32 bit enterprise edition.
Having 2 logical drives helps you to increase to diminish the freeze situation at whole desktop level.
Usualy the controller have a bigger transfer capacity than harddrives combined.
If accounting app that freeze it will not affect the operating system and the other users
Also you will be able to investigate the real cause by moving one by one apps as the problem persist.

Using a 32 bit operating system will use only 4GB of ram for applications, rest of memory is alocate via PAE system and can be used only by specific applications (like SQL server)

So if the platform permit i recommend to upgrade to a 64bit operating system (and you will see operating ussage close to 16GB and a lower swap ussage)

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andyalderSaggar maker's bottom knockerCommented:
If you can't decide which of your apps/storage needs the most throughput then a single RAID 10 is ideal, if accounting app is not busy the other applications get the benefit of the extra I/O. If you were to have two seperate arrays then you would quite likely be wasting performance while one array runs flat out and the other one is idle.

If you have 8 bays then of course keep the original pair for the OS, pagefile and perhaps transaction logs but don't split the new 15K disks into 2 arrays.
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