W2k12 R2 System Partition Size and Paging File

Have a new HP ProLiant DL380p W2K12 R2 STD the will be running Hyper-V host role only in GUI mode with 3 to 4-VM's.  OS license will be stacked for the 4-VM allowance and storage will be "OBR" RAID10 8-disk setup.  

Several questions:
1. W2K12 R2 OS install- What is a good partition size for the OS install with minimum paging file for dumps?  
2. Is it beneficial to create a separate partition for the paging file ONLY (server has 96GB of RAM installed) or is it OK to put that on the large D: partition with the VM's?
3. Is the recommended paging file size still the 1.5x the physical RAM installed?  I am seeing conflicting information on that and with 96GB of RAM that is an awfully large paging file.
valcoAsked:
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Lee W, MVPTechnology and Business Process AdvisorCommented:
1. W2K12 R2 OS install- What is a good partition size for the OS install with minimum paging file for dumps?  
I would do 120 GB EXCLUDING pagefile (see below).

2. Is it beneficial to create a separate partition for the paging file ONLY (server has 96GB of RAM installed) or is it OK to put that on the large D: partition with the VM's?
Disk is the slowest system, you DO NOT want the pagefile (or OS partition on the same partition as your VMs.  Ideally, your VMs will run off SSDs or at least good RAID 10.  It CAN be a good idea to put the page file on a separate DISK, but not a separate partition per se.  The separate partition will just ensure it doesn't fragment whereas a separate set of spindles (or SSD) will keep the disk from contention with other system resources.

3. Is the recommended paging file size still the 1.5x the physical RAM installed?  I am seeing conflicting information on that and with 96GB of RAM that is an awfully large paging file.
The above said, for a hyper-V server, you never want the system paging much to begin with.  Leave it as system managed on whatever disk you configure it on.

Additional reference:
http://www.aidanfinn.com/?p=15659
and
http://support.microsoft.com/kb/2860880
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valcoAuthor Commented:
Thanks Lee.  Couple things on your comments:

I have one RAID 10 array with two logical drives.  The hard drives are HP Enterprise 10K SAS-2 6G on a P420i 1GB FBWC Smart Array Controller.  In your opinion is this adequate for "at least good RAID 10"?  SSD were not in the budget for this project.

Current Setup:
1-Array
Logical 1- OS (currently set to 220GB...may change to 120GB though per your recommendation)
     -I will leave paging file here as system managed
Logical 2- VM's
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valcoAuthor Commented:
I have an additional question....looking into Lee's 120GB recommendation and SSD's I was wondering if the following configuration would be recommended over my current configuration.  This is a new server project and buying all SSD's was not an option for the entire project because of cost.  However, would I benefit (performance) by installing the OS/Hyper-V Host Role on 2-120GB SSD's in a RAID 1 config and then have the remaining 6-600GB SAS-2 10K larger drives in a RAID 10 config for the VM's?  I realize I would lose a little disk space in this configuration on the RAID 10.

Current:
8- HP Enterprise 600GB SAS-2 10K in RAID 10
1 Array; Logical 1- OS, Logical 2- VM's

Possible New:
2- 120GB HP Value Endurance Enterprise SSD in RAID 1
6- HP Enterprise 600GB SAS-2 10K in RAID 10
2 Arrays; 1 for OS with SSD's, 1 for VM's with SAS-2 10K drives
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Lee W, MVPTechnology and Business Process AdvisorCommented:
Disk subsystem, as I mentioned before, is almost certainly going to be your biggest bottleneck.  It's speed and configuration will ultimately determine how well the system works.  That said, I have no idea your I/O demands for the various servers. Or configurations.  For heavy I/O apps, I would either put them on SSDs or separate mirrors.  For lighter I/O, You can combine them onto single disks.  In some cases, you may have specific workloads on a specific server that require fast I/O but others that don't.  You could, for example, put the OS/Boot drive on one set of spindles with 3 other OS/boot drives and then put your critical data on it's own set of spindles.

Another thing to look at - RAID controller cache.  Intel based systems (including Intel Boards) offer the ability to use an SSD as a cache.  Server 2012 R2 using Drive Spaces also offers this as well as a tiering structure when you mix Faster and slower drives that can put frequently used data on the faster drives for quicker access.  These strategies can SIGNIFICANTLY improve rights and reads of commonly accessed data.  But at the end of the day it's pretty near impossible for me to say what will work best.  Hire a consultant to analyze your environment and plan your disk subsystem.  Or spend a dozen or more hours learning to do it yourself and planning it appropriately.

Finally, the above said, I'm lazy (and cheap, for me).  My own Hyper-V host is running off a single 7.2K SATA drive with backups.  I would NEVER, EVER do this or recommend this to a client.  BUT, the point is, I have 7 VMs running on that single drive (well, actually, I split it up a LITTLE onto a second disk.  Performance is DOG slow at times... but for me and my 1.5 man shop, it's acceptable.  One of these days, I'll upgrade the systems, but until then (and I've been saying that since I put 2008 R2 in place on the same hardware).
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