raid configuration

[idata]

I have what might sound like a silly question to the experts here. I built a 16 drive server. I purchased an Intel Raid card RS2SG244. I would like to use an OS/boot drive at about 200GB and the rest of the spanned array (4x2tb raid 10) for data. The other drives I will create 3 more raid 10 arrays, instead of one 16 drive raid 10, according to posts I have read. OK, the question is: what is the difference between creating a 3.6 GB raid 10 array and partitioning it in windows to 200 GB and the remainder for a data partition, or making a 200 GB virtual drive and the remainder in another virtual drive configured with the Raid bios on the hardware. I will be running Windows Server 2008r2 Standard x64. There has to be a reason to do one over the other. I used a live chat with an Intel Tech, with little clarity. He claims it is personal preference. Anyone?????

Scott

[Edward_Z_Intel]

Here is the logic:

1. MBR disk can't be larger than 2TB. GPT disk can. If you make your 3.6TB VD an MBR drive, only the first 2TB is accessible.

2. A disk is either MBR or GPT. You can't create a MBR partition and another GPT partition on the same drive.

3. Booting from GPT disk takes additional steps. See the http://www.intel.com/support/motherboards/server/sb/CS-031158.htm GPT White Paper.

If you want to avoid all those additional works to boot from a GPT disk, create a 200GB VD and make it the boot drive.

[idata]

Thanks Edward. I followed the directions and it will not boot to the OS. I made 2 VD's 200gb and 3.4tb. I installed the OS on the 200gb, made it the boot drive in the raid bios and no boot. I even loaded it mbr and changed it to GPT when the computer management service starts, works until a reboot. I'm almost at the point to get a couple 250gb RE4 drives in raid 1 and make them the boot drives and pagefile drives....Starting to feel a little silly. I've never had configuration issues like this, all of my servers have multiple partitions under 2048 on them with no issues....GPT for 4TB arrays for data backup, no issues. I sure would like to talk to you at work one day, I hate typing this much..

Scott

[Edward_Z_Intel]

If you have a 200GB VD then you don't need to follow the instructions in the white paper - use MBR and legacy boot. The 3.4TB data VD should be GPT disk.

[idata]

I thought you couldn't use MBR and GPT on the same drive??

[Edward_Z_Intel]

That's why you created 2 VDs right? Each VD appears as a physical drive to the OS.

[idata]

Maybe clarification so everyone is on the same page...

ohiopyrotech, did you create a raid 10 array on the controller with 4x2TB drives and then cut the array in to two virtual drives of 200GB and the remaining space from within the raid controller (Megaraid ??) interface ?.

If so then these virtual drives will be presented to the OS as two completely separate drives and so you can use them as such when you format etc.

From reading, correct me if wrong please, I suspect you may be creating a 4x 2TB array on the controller and a 4 TB virtual drive and then partitioning it in Windows to the 200GB and the remaining space as separate partitions rather than virtual drives.

Regards

SL 

[idata]

Smon,

I used the RS2SG244 controller interface to create both the spanned raid 10 and the virtual drives. I created a 200GB VD and a 3.4TB VD. I used MBR on the 200GB running Server 2k8r2 and GPT on the 3.4TB drive, the MBR partition goes with the 200GB in windows and I created simple volumes (in windows disk management utility) for the GPT. Actually I have a 28 port Intel Raid card with 20 drives on it in 4 - 4TB RAID 10 VD's and one RAID 10 set with 200GB and 3.4TB. I am pleased at the read and write performance so far...

Scott

[idata]

Hi Scott,

Good to see you have it working.

The card you have would appear to be a rebadged LSi 9280-24i4e and it should be able to handle the 24 drives fine (24x approx 150MB/s burst = 3600MB/s on a PCIe x8 giving 4GB/s). The only issues you are likely to face is if you choose to populate with fast SSDs in the future (unlikely scenario for most people I would imagine).

Just as an aside, more for anyone reading in future who may not be aware, http://en.wikipedia.org/wiki/Standard_RAID_levels# .22RAID_10.22:_a_stripe_made_of_mirrors Raid 10 is a mirrored stripe set rather than a http://en.wikipedia.org/wiki/Non-RAID_drive_architectures# Concatenation_.28SPAN.2C_BIG.29 span.

Regards

Si

[idata]

Simon,

In the card utility, you have to create a drive group of 2 drives twice and then "span" the drive groups for RAID 10. That's why I used the term span....

Scott

[idata]

Hi Scott,

Seems that LSI have rewritten the definition of Raid 10 in their manuals. They are using Raid 10 as a spanned mirror rather than a striped mirror. Guess you can do that when you are a top player in your field .

Regards

Si