I'm in the process of building a NAS system - It has 8 1TB drives, which I am currently building as a RAID 5 array. It's using a 3ware hardware raid controller.

I've also installed a single 250gb drive into the top of the unit (there is an additional drive bay here) My intention is to use this drive for the OS / boot drive.

How do I go about setting this up? By that, I mean, do i have to set some jumper on the drive / set a setting in the bios, to boot from my single drive, rather than my RAID array? I've plugged the SATA cable from the drive into the mainboard - SATA 0 (i think, at least)

Also, how should I format my RAID array, once it's finished formatting? Should I be using GPT - I will install Windows Server 2008 x64 Standard as the OS on the above mentioned 250gb drive

  • Duplicate serverfault.com/questions/79643/… You should edit your original question where there are already valid answers rather than start a new one
    – MDMarra
    Oct 30, 2009 at 15:17
  • If this is important data, please re-think your RAID strategy - RAID 5 really is not a safe technology with most RAID controllers due to the way parity is not calculated atomically. Oct 30, 2009 at 15:19
  • I believe Phil is referring to the RAID5 Write Hole which also affects RAID6. A battery backed up cache can help reduce this problem but does not eliminate it. I would avoid RAID5 for a different reason. The chances of running into a unrecoverable read error (URE) with that much space is high. With SATA drives this rate is every 10^14 bits or about once every 12TB. So statistically a RAID5 volume of that size will have about a 50/50 chance of failing during a rebuild due to a URE. I would go with RAID6 to avoid this. This doesn't avoid the Write Hole problem though. Oct 30, 2009 at 16:00

2 Answers 2


Generally yes there's a BIOS boot order that you would have to set.

In similar situations I put the OS on two mirrored drives and the data on RAID 5 (or something appropriate).

You will have to use GPT, as MBR stops at 2TB, and you will have 7.

As a note of caution, we've had more 1TB disks fail than any smaller disk size; I would practice how failover works before going production with this.


There should be a boot order setting in the BIOS.

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