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I have 6 x 1TB SAS for my new server. I want to create 3 partitions: one for OS, one for Virtual Machines, one for share data. There are 2 options for me:

Option A: Create 3 Virtual Disks in RAID Configuration Utility

Option B: Create 3 Partitions during OS Installation

Given that the disks will run in RAID6, which option is better?

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You don't mention anything at all regarding software, what's your host OS? it matters a lot. – Chopper3 Mar 2 '10 at 10:15
my host is Microsoft Windows Server 2008 R2 Datacenter x64. – Raptor Mar 4 '10 at 7:39

You really do not want to put an operating system, virtual machines and shared data across a single RAID-6 array. The random write performance will grind you to a halt.

My suggestions is that you create 3 separate RAID1 arrays for OS, VM's and data (with whatever partition scheme you want).

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RAID1 is slow. As in my case, we need high data speed for data sharing, so I do not prefer RAID1. – Raptor Mar 4 '10 at 7:38
From where have you gotten the impression that RAID1 is slow? It's certainly not slower than RAID6, unless you are doing extreme amounts of sequential read streaming. – pauska Mar 4 '10 at 11:23
up vote 0 down vote accepted

I end up using the following method:

First, I tried to make 1 4TB RAID6 virtual disk, and do the partition job in Windows Server 2008 R2 installation. However, I encounter a problem. Here is my INTENDED partition layout:

  1. 100GB NTFS for OS
  2. 2TB for Data #1
  3. 1.5TB for Data #2

However, the Windows does not allow me to use all the spaces in the 4TB virtual disk. Here is the layout:

  1. 100MB : System Reserved
  2. 100GB : OS
  3. 1947.90GB : Data #1
  4. 1676.00GB : Unallocated Space

I cannot make any partition for the #4 unallocated space. Is it a limitation of Windows Server 2008 R2?

I end up splitting up the RAID6 disk group into 3 virtual disks. problem free.

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Since you are only asking which of option A and B is best, given RAID6 will be used, I would recommend option B.

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